Running a Boss Battle as a Skill Challenge

A year or two ago, I ran an adventure where the PCs were asked by an underground civilization of gnomes to help with a problem. The gnomes had been using clockwork mining equipment for years, and recently the machinery had gone out of control and begun attacking the miners. 

Over the course of the adventure, the PCs learned that the issue was that the bound elementals which powered the mining equipment were being set free by a gnomish extremist faction. These gnome extremists considered binding the elementals this way to be tantamount to slavery. By the end of the adventure, some of the PCs were inclined to agree.

The final battle of this adventure happened when the gnomes' largest piece of mining equipment, their massive excavator (for which I had a great miniature) smashed through the cave wall of their underground city and began approaching the capital, intent on demolishing as many buildings as possible.

We've all run those boring battles where the fighters run up and smash monsters and the monsters smash back. I wanted this one to be something different. Something special. So as the PCs rolled initiative, I laid out for them the rules that would govern this battle. Primarily, they needed to know that the excavator could not be hurt by normal weapon attacks or by spells. What? Yeah. The thing was just too massive. It would be easier to destroy a house with your swords and magic missiles than it would be to destroy this two-story steel behemoth. 

Instead, the characters were left to figure out during the battle how they could possibly stop this thing from destroying the city. To help, I placed a 3x5 file card in front of them. It read:

Investigation, DC 12
Study the excavator, and try to determine an effective way to attack it

So while the excavator slowly advanced on its turn, getting closer to the gnome city, the PCs could attack the clockwork mining equipment, or spend their action making that investigation check. Each investigation success would give them another file card, at random, giving them more options. I placed six buildings on the map and let them know that their goal was to save as many as possible.

Behind the screen, I had what the excavator would do each round all planned out:

Round 1: Excavator moves forward and fires its eye beam at a building, damaging it to 50%
Round 2: Two clockwork drills appear and begin fighting. Excavator moves forward and makes arm attacks at any characters in range.
Round 3: Excavator moves forward and throws a mine cart at a PC (ranged attack)
Round 4: Three dwarven guards appear to help. Excavator moves forward and fires its eye beam at a PC - lots of dust in the air creates a heavily obscured area; if the targeted PC succeeds in a stealth check then the eye beam has disadvantage.
Round 5: Excavator makes arm attacks, but does not move. Instead, it shakes violently if anyone is on it - any PCs atop it have disadvantage on their acrobatics checks to stay up this round.
Round 6: Excavator moves forward and reaches up to smash at the cave ceiling - everyone within 10 feet of it takes 6d6 bludgeoning damage from falling rock, DC14 DEX save for half
Round 7: Two more dwarven guards appear. Excavator moves forward and makes arm attacks
Round 8: Excavator moves forward and makes arm attacks
Round 9: Excavator moves forward and fires its eye beam
Round 10: Excavator reaches and destroys the first building, and one additional building each round.

The rest of the cards were revealed in random order, but here is the first:

Battle Goal: Disconnect Arm (x2)

Get to each shoulder in order to disable that arm, either by mechanical sabotage or simply by smashing them.

 • Climb up to the shoulder: 1 action, Athletics DC13

 • When a character begins his turn atop the shoulder, he must make a DC10 acrobatics check to remain on his feet or else fall, taking 2d6 falling damage.

 • Disable the arm: 1 action, Athletics DC14 or Sleight of Hand DC 15 - a success disables the arm. Two sleight of hand failures jam the mechanism and raise the DC to 16

 • This battle goal may be accomplished twice.

I don't recall the specifics of the arm attacks, but they were infrequent, inaccurate, and very damaging.

Battle Goal: Disable Eyebeam

Get up to the eye and extract the fire elemental within

 • Climb up to the eye: 1 action, Athletics DC15

 • When a character begins his turn at the eye, he must make a DC12 acrobatics check to remain on his feet or else fall, taking 3d6 falling damage.

 • Extract the elemental: 1 action, Arcana DC 14

    Success: eyebeam is disabled; hostile fire elemental appears

    Failure: eyebeam gets attack of opportunity on PC

The eyebeam was dangerous not only because it could attack at range, but also because it could destroy buildings before the excavator had even reached them.

Battle Goal: Sabotage Wormfoot Drive

The excavator will soon be reaching structures!  Sabotage three legs on one side in order to disable movement.

 A single leg can be disabled in one of two ways:

 • Pry and wrench the leg, rendering it useless: 1 action, DC 16 Athletics check. On a failure, the character is injured by the leg: 6d6 bludgeoning damage, DC14 DEX save for half

 • Do a total of 20hp damage. Any damage of less than 5hp is not recorded, and the leg is immune to piercing and resistant to slashing damage.

 • This battle goal must be completed three times to stop the excavator from moving entirely.

I think I invented the term "wormfoot drive", but I'm not sure. I like it.

Battle Goal: Extinguish Steam Mephit Chamber

Putting out the boiler on its back will slow it drastically 

 • PCs should describe how they go about this task

 • Extinguishing the chamber slows the excavator by 50%

This should be the easiest of the challenges. Allow the PC to describe how they will go about extinguishing the mephit chamber, encouraging creativity, then give them a DC 8 check for success.

Battle Goal: Rally Support (x2)

Looking around, you see many gnomes watching in terror as the mining equipment advances inexorably toward their homes. If only someone could convince them to help!

 • Convince gnomes to help: Persuasion DC 13

 • Success brings NPC allies

So this was my skill challenge boss battle. While the lesser traditional clockwork minions attacked, the excavator ran through its paces. It worked very well. PCs were forced to divide their efforts between the traditional monsters and the real threat. In the adventure I ran, the PCs managed to stop the excavator after two buildings were destroyed. The gnomes weren't very happy about it, due largely to some other shenanigans that had gone down earlier, and they threw the PCs in jail for their trouble. Shortly after, a sympathetic gnome official had them released, and later delivered a clockwork automaton to help plow fields on a PC's farm.

If you decide to use a variant of this in your own game, I suggest that you make up the attack stats of the excavator on your own, and scale the entire encounter to your PCs' level. It was a fun adventure, and I hope that someone else is able to use it and get nearly the same kind of enjoyment from it that we did.

What does a "High Magic" Setting Look Like?

 

The majority of the games I've run over the years have been homebrew, and the bulk of them have been low-level games in low-magic settings. I do recall running Dragon Mountain back in the 90s, and I've been a player in a few games that may have gone as high as level 10, but those games have been the outliers. My friends and I have generally found D&D's sweet spot to be between levels 3 and 8.

So what is a "high-magic" setting in Dungeons and Dragons? Generally, it's defined as a higher-level setting in which magic is commonly accepted as a part of everyday life. 

In my opinion, no existing setting has really taken every aspect of this into account. Eberron has done well in taking some small steps in that direction, but in this article I'm going to explore a number of aspects of a high-magic setting which I don't generally see discussed.

Consider for a moment this example.

DM: Okay, you've still got 3 days until the Baron needs you, what's everyone doing?
WizKnave: I want to go back to the market.
Players: (collective groan)
DM: Again?
WizKnave: No, I've got a plan. This'll be quick. Is that silk merchant still there?
DM: The one you charmed two days ago? He'll remember you. He lost a lot of gold.
WizKnave: Got it. That's fine. Do I see him?
DM: Sure, you find him in a few minutes in the open air market.
WizKnave: Okay, I stay far back out of sight and look for his gold coffer.
DM: After your whole mage hand thing, the merchants are all using heavier coffers.
WizKnave: No problem, I expected that. Is he selling his silks alone?
DM: Uhh, no. He's got a young woman with him today.
WizKnave: Damn, two of them. I guess the minor illusion trick is out. How many other people are near them?
DM: There lots of people in the market, but nobody within maybe five feet right now.
WizKnave: Great. Okay, I wait until nobody is looking and cast sleep on them.
DM: Sleep. Well, uh, great. These aren't adventurers. I guess they fall asleep. The vendor at the next booth over is also in range, and he falls into his table with a loud crash. People are looking.
WizKnave: I stay back and wait. 
DM: Okay, some people have gone up to check on them.  
WizKnave: I move up with them, behind them, and take off my cloak, throwing it over his coffer. Then I take another few seconds "checking". Not long enough for him to wake up. Then I pick up my cloak with the coffer full of gold in it and walk off.

The truth is that in a setting where magic exists, even if it's low-level magic, it's going to create such absolute chaos that it's nearly impossible to envision all the things that someone with access to even just first level spells might try. But in a world where these things have existed for centuries, people living in that world would have seen it all. This is our challenge as DMs: to imagine the myriad unexpected uses of magic.

Law Enforcement

As cited above, something that's likely to come up in gameplay is the use of spells to engage in extralegal activities, whether it's breaking into the villain's manor or eavesdropping on the cult of Vecna. Still, any civilization in which magic exists will certainly be accustomed to and account for magical threats. Your PC is not going to be the first one to have ever thought to charm the guards or wild shape into a mouse and sneak past a checkpoint.

There's reason I've focused primarily on first level spells and cantrips in my examples. Even these low-level spells and abilities can completely throw a wrench into an adventure if they catch you off guard. Once you begin to add teleportation or high-level divination into the mix, it gets worse.

If these abilities exist, then criminals will have access to them. And even if a scroll of teleportation costs 1000 gold, then any vault in the city with more gold than that becomes a valid target. Finding such a vault with divination magic wouldn't be difficult. This means that any and every store of wealth will need magical protection. Anything else is just a plot hole - a DM oversight. Every well-off household and market will have defenses against illusion, divination, and teleportation. This kind of high-magic security system would be at least as common as modern-world security systems. The alarm spell would be ubiquitous, and versions of it which cover greater areas and work in more intricate ways would most certainly exist. Don't limit yourself to published magic when it comes to worldbuilding.

Counters such as the alarm spell would be central to a magical society being able to function at all. The city's government would absolutely need to have the most skilled wizards, able to create permanent abjuration and divination effects to protect cityfolk from arcane criminals. City guards would be equipped with gear that allowed them to detect magic and invisibility, and they would all have access to silence spells. They would regularly watch marketplaces using basic divination, and make sure to take note of any suspicious magic. The primary things they would be watching for would be illusions, mage hands, detect thoughts spells, and enchantments such as charm person.

When criminals are caught, court proceedings and trials in a magical society would likely be far different than they are in real life. After making sure any magical protections against divination are removed from a suspect, putting them in a zone of truth would quickly reveal their innocence or guilt. And any murder victim could be spoken to postmortem to learn the identity of the killer. These procedures would be standard everyday business for law enforcement in a magical society. Remember this the next time your PCs leave the bandits' corpses in an alleyway.

Magical Society

One of the primary questions that should come up as you're designing your high-magic city is what type of civilization are you building? Is it a democracy wherein all the races live together in an urban utopia? Is your city ruled by the priest-emperor whose dark justiciars patrol the streets meting out heavy-handed justice? Or does the council of mages run the city, making liberal use of detect thoughts to ensure public compliance and weed out agitators?

In a utopian society, non-magical disease can easily be wiped out, low-level druids can ensure that no one ever goes hungry, and even life-threatening injuries can be made trivial with first level healing. On the other hand, in the type of civilization we more often see in D&D settings, the powers that be could ensure that they remain in power endlessly by employing Contact Other Plane to identify threats well before they happen. Thus, PCs who may not yet have begun planning to act against the government may find themselves targets of pre-emptive justice.

Most settings will find themselves a place somewhere between a dark dystopia and a perfect utopia. In such a well-functioning society, the local government may require those who employ the arcane arts to register, much as we have licenses to drive a car. Casting spells without a license may result in fines or jail time, with violations resulting in revocation of your arcane license. Similarly, using magic in the commission of any crime is likely to result in your arcane license being revoked. And of course, any interaction with law enforcement which involves magic is likely to begin with the guard asking to see an arcane license.

Arcane Infrastructure

In a world where magic exists, it only makes sense that the populace would want to make use of it to improve their quality of life. It's difficult to imagine all the ways in which this would manifest, and most of these ways won't likely come up in your typical D&D game, but let's take a cursory look at a few of them.

Transportation

In a high-magic setting, horse-drawn carriages and traditional ocean-going ships seem quaint. Perhaps the ships sail the skies, and flying rickshaws whisk commuters around the city. Any high-magic city worth its salt will also have teleportation circles set up to trade with faraway communities, although these are likely to be well-regulated and well-guarded.

Agriculture

Traditional medieval societies dedicated a huge portion of their resources to growing food, and farming was by far the most common profession. With the aid of magic, fields can more quickly be plowed, crops can more easily be harvested, and peoples' time freed for other endeavors.

Communication 

Sending Stones are a Dungeons and Dragons equivalent of a telephone, and in a high-magic civilization, they would likely be in strong demand, and thus quite popular. Animal Messengers might be a slightly more affordable, and thus more common, option. As such, there are likely messenger services which specialize in this kind of communication.

Public Works

The city would most likely employ a number of mages who specialize in telekinesis, using them in construction projects to lift what would otherwise take many men, or perhaps two or three ogres.

The city might also require churches to engage in public service, casting purify water at outhouses or on sewer systems regularly to improve public health.

Education

Public education is a modern convention. In a medieval fantasy setting, apprenticeships and religious education would seem more likely. But in a high-magic city, students may be taught cantrips at a young age. Perhaps school is a privilege available only to the wealthy, but if language, math, and history are taught, then basic arcana is likely a subject as well. 

Commerce

Every campaign is going to have its own rules about buying or selling magic items. Xanthar's Guide to Everything has rules about buying a magic item which involve spending time and money looking before determining whether the item is even available, and rules for selling magic items which involve soliciting and entertaining offers. These are excellent starting points, but in the end these matters are up to the DM. I've run campaigns where magic items are exceedingly rare, and others where you can go down to ye olde magic shoppe and peruse a collection of wands and enchanted blades. In a high-magic setting, you're more likely to fall closer to the latter. 

But these are all items for use by adventurers, and most of the citizens of your high-magic city aren't adventurers. These good folk will be far more interested in magical hair cream to cure baldness, self-cleaning chamber pots, maidenweed to act as a contraceptive, and warding amulets that drive off biting insects. It's easy to go down the rabbit hole on this and come up with dozens of common magic items which adventurers may not care about, but which would change the lives of commoners. The Rod of Laundering means no more days spent by the river with a basket of soiled clothes. Cooling runes can lower the temperature in an area by ten degrees - perfect for those summer months. And quasi-legal love potions, which turbo-charge the imbiber's libido, are a hot grey-market seller.

With the prevalence of magic, it's entirely feasible that many traditional professions may have disappeared entirely. What use is a translator when Comprehend Languages exists? Traditional lock-and-key setups may lose all relevance when Knock spells are commonplace and Arcane Lock spells are cheaper than mechanical locks. And the field of medicine is entirely moot when you can opt for magical healing.

Create Food and Water is a third level spell, higher level than most discussed here, and the spell description does mention that the created food is bland. But a chef could easily season that food, or a wizard could modify the spell to create more appealing meals. A lower-level version of the spell which creates far less food of a more gourmet variety could easily lead to the high-magic version of fast food, summoned hot and fresh on demand by your sorcerous chef.

Illusionists in our high-magic city may have the most illustrious career of all. While illusion is all too-often concerned with deception, it can be far better employed in theater. In a world where the technology of photography doesn't exist, audiences can still be entertained by theater productions with lifelike dragons breathing fire right inside the opera house, all with zero danger to the audience. The illusion theater industry has the potential to bigger and more culturally impactful than 21st century movie theaters.

The possibilities for magic in this kind of fantasy setting are endless. And the more time you spend thinking about these minor details, the better fleshed-out your high magic setting will become.

Concealment and Cover in 5th Edition

We're opening today with a close look at some rules which I think get overlooked at many tables, my own included. Those are the rules for concealment and for cover in 5th edition D&D. Nearly every modern action film features a gunfight with people ducking around corners, behind cars, and dropping flat to avoid gunfire. Similarly, there's no reason a knight shouldn't duck around a corner to avoid those scorching rays. Your druid could easily lay down a fog cloud to cover the barbarian's charge towards the enemy archers. Every dungeon corner is cover, and every hedge is concealment. You just need to use it.

Cover

Cover is some solid surface standing between you and the person attacking. It could be a wall, a pillar, or even a creature. This is important, because while 5th edition Dungeons and Dragons doesn't include a penalty for firing a weapon into melee combat, it does specify that creatures can provide cover, which can amount to the nearly same thing. The players handbook defines cover as follows:

There are three degrees of cover. If a target is behind multiple sources of cover, only the most protective degree of cover applies; the degrees aren't added together. For example, if a target is behind a creature that gives half cover and a tree trunk that gives three-quarters cover, the target has three-quarters cover.

Half Cover

A target with half cover has a +2 bonus to AC and Dexterity saving throws. A target has half cover if an obstacle blocks at least half of its body. The obstacle might be a low wall, a large piece of furniture, a narrow tree trunk, or a creature, whether that creature is an enemy or a friend.

Three-Quarters Cover

A target with three-quarters cover has a +5 bonus to AC and Dexterity saving throws. A target has three-quarters cover if about three-quarters of it is covered by an obstacle. The obstacle might be a portcullis, an arrow slit, or a thick tree trunk.

Total Cover

A target with total cover can't be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.

Cover can be a game-changer. Every forest has trees to hide behind, every dungeon has corners. There is nearly always some kind of cover, and if your mage isn't hiding when he's casting those firebolts, then you're giving up an advantage.

Back in 3rd edition, there was a feat called Shot on the Run. It had many prerequisites, but I always wanted to play a character with that feat, because I thought it was overpowered bordering on broken. What did that feat allow you to do?

When using the attack action with a ranged weapon, the character can move both before and after the attack, provided that the character's total distance moved is not greater than the character's speed.

This meant that you could begin your turn in total cover, completely untargetable by enemies, move out, take your shots, and then return to total cover, never giving your opponents any chance to return fire. And while they could certainly ready attacks and wait for you to appear, you'd generally have made a number of attacks before they figured out that they needed to do that. Well, guess what? In 5th edition D&D, everyone can do that without taking any kind of feat. You can bet that I'm going to have the NPCs I run in my game session this weekend doing this to PCs.

Firing into Melee

As I alluded above, 5th edition doesn't have specific rules for firing into melee, but the situation is neatly handled by the rules for cover. Creatures can provide cover, and it doesn't matter if they're friends or enemies. If you're firing into melee, then you look at the positions of the relevant combatants and determine whether your target has half cover. It's only a +2 to armor class, but that can sometimes make a difference. 

It would be a house rule, but a DM could determine that there's a chance you accidentally hit the creature providing cover. Even a slight chance that you may accidentally hit your barbarian with that disintegration ray might make you think twice. My suggestion for a house rule would be that if the ranged attack missed the intended target, you roll again with disadvantage to hit the target providing cover. This takes the target's armor class into account, and the disadvantage makes it more forgiving than a straight hit roll.

Prone

According to the players handbook, an attack roll against a prone creature has advantage if the attacker is within 5 feet of the creature. Otherwise, the attack roll has disadvantage. This means that if you don't think your enemy can get into melee with you before you can stand up, it might make sense to drop flat. However, since you have disadvantage to all attacks while prone, you'll probably want to spend half your movement getting back up before making another ranged attack.

Range

Of course, a big part of the reason these rules never come up is range. When you find yourself fifteen feet away when you're rolling initiative, taking cover doesn't often make as much sense. But if you're able to see the enemies from max bow range, then it's a different story. I once had a first level party take down a charging ettin (just) before it got into melee simply because the ettin was stupid and the players started at the longest possible range, giving them multiple rounds of attacks.

Concealment

Cover is relatively straightforward, providing armor class and save bonuses. Concealment is a bit stickier. Lighting in 5th edition is separated into three categories: bright light, dim light, and darkness. Bright light allows for normal sight, and all daytime conditions, even if overcast, are considered bright light. Dim light such as twilight, shadows, or bright moonlight creates a lightly obscured area. Darkness creates a heavily obscured area. This happens underground and at night, even on most moonlit nights.

Previous editions of D&D defined infravision, low-light vision, and even ultravision. Those are all gone in 5th edition, so forget about your elf seeing heat signatures. 5th edition includes Darkvision, which allows a creature to see in darkness as if the darkness were dim light, and in dim light as if it were bright light, but the range of darkvision is generally limited. So if your dwarf has darkvision out to 60 feet, then that demon standing 70 feet away might as well be invisible.

Blindsight allows a creature to perceive its surroundings without relying on sight at all, which means if a creature with blindsight is inside a fog cloud or in magical darkness, it can effectively "see" just fine. Truesight allows a creature to see in normal and magical darkness, and it can also see through invisibility and illusion magic. A creature with truesight can even see into the ethereal plane and can perceive the original form of a polymorphed creature.

So what does all this mean? All these different types of vision and lighting conditions distills down to one thing: how obscured is something from your perception? If something is lightly obscured, then you have disadvantage on perception checks in regards to it. If it's heavily obscured, then vision is blocked entirely. This means that if you're in a fog cloud, you're effectively blind. And if you're firing your bow at a target who's inside a fog cloud, you have disadvantage because you're effectively blind as to where it is.

There are only three different situations which would play out here. First, when both the attacker and the target are inside the cloud: The attacker has disadvantage because he's blind, but the defender has disadvantage for the same reason. So the attack roll is made normally, as the advantage and disadvantage cancel each other.

The second situation occurs when the attacker is inside the cloud, attacking a target outside the cloud. The attacker is blind, since he's inside the cloud. It's true that he's effectively invisible to his enemy, but for purposes of this attack, he has disadvantage.

The third situation is the most interesting: when an attacker is outside the cloud, attacking a target who's inside the cloud. The target is in a heavily obscured area, and is effectively invisible, so the attack is at disadvantage. But additionally, the attacker doesn't necessarily know where inside the cloud the target actually is. The rules for dealing with the situation here are vague, but as a DM, I rule that the attacked needs to choose a 5 foot square to target. If the target is in that square, then the attack with disadvantage can be made normally. Since any target in the cloud might still make noise, I allow a contest between the target's stealth and the attacker's perception - this check doesn't cost either of them an action. If the perception check wins, then the attacker hears something and knows which square the target is in. Otherwise, he's got to guess.

In my mind, the best tactic for anyone trying to use a cloud effectively in combat is to pop out, make attacks, then pop back into the cloud. While this may result in attacks of opportunity, it still works well in many situations, and it works best for rogues, who can disengage as a bonus action.

If you use cover and concealment against your players, they'll get the idea real quick.

Other resources on this topic:

• Stack Exchange: How Does Concealment work in D&D 5e?
• D&D Beyond: Vision and Light
• Arcane Eye: Cover in 5e

Mission Statement

I've been running Dungeons and Dragons games on and off for 35 years. I've run games in every edition going back to the red box I got from Bradlees for Christmas when I was 11 years old. 

In 2024, there are a near-infinite wealth of resources online for running your D&D game. But not all of them are good. So many of them focus on selling a book the blog's publisher is selling or on product endorsements to gain advertising dollars. Personally, I've got no interest in any of that. I just want to share the cool stuff I think up, and point out other cool stuff I see online to boost the signal of ideas that are likely to improve other peoples' games. I simply have so many ideas, scenarios, thought pieces, and bits of rules analysis that I can't help but feel it's time to write it all out on a blog.

So this blog will contain just that: DM tips, house rules, suggestions for game scenarios, reviews of oft-forgotten rules, and adventure hooks. For inspiration, I look to the only two other blogs out there I'd like to (in some way) emulate: Sly Flourish, run by The Lazy GM, and Hipsters & Dragons, run by a British gent named Duncan. I also frequent the DM Academy subreddit, which has intermittent moments of brilliance. If you're up for it, I recommend you visit all of these.

As for myself, I've got quite the busy life, and so I can't guarantee that I'll be able to post every week, or even every month. Life is busy, and I aspire to quality rather than quantity.