Monstrous Compendium Vol. 1: Spelljammer Creatures
Frozen Sick
D&D Beyond Basic Rules
Basic Rules (2014)
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Monstrous Compendium Vol. 1: Spelljammer CreaturesFrozen SickD&D Beyond Basic RulesBasic Rules (2014)Sign in to view your library & saved favorites.
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TW: corpses, body horror??
So, my players are facing a pretty big boss next session. It's an undead mass of corpses/flesh that slowly dissolves and assimilates with the people it eats. It's like a hivemind for a ton of ghouls in this cave system my players are in. I'd really like to make an original boss, something with a lot of tricks to it and strategy, but that's my most optimistic hope, since I'm not exactly the most experienced. Any advice? I've done bosses before, but for the most part I just took a statblock and renamed it, or just used a normal creature/npc.
Star Trek enthusiast, UTDR fan, Dean Winchester lover, and aspiring author/artist.
SPAMTON G. SPAMTON FOR [[present]]IDENT!
Grab a stat block for the sort of critter you want, at more or less the right CR and combat style. Don't forget the minions when planning the encounter.
Give it legendary actions and saves.
Make sure it has enough HP that the party can't kill it too quickly. Defensive abilities, such as sacrificing minions to soak damage, reduce how tanky it needs to be. (And they're more flavorful.)
Replace or reflavor the attacks to fit the boss better, keeping the attack numbers and damage similar.
It sounds like this thing is sessile, so give it some kind of ability (probably one of its legendary actions) to get people out of its face.
Another one of its actions or legendary actions should probably be spawning a new ghoul.
Given that ghouls' signature ability is paralyzing people, a big mechanic of the fight could be the ghouls or the boss grabbing a paralyzed PC, bringing them over to the boss, and it starting to digest them. Take a look at the various critters with grapple or swallow mechanics to see how this could work.
Figure out at least one out for if you've overpowered the thing, and you're looking at a possible TPK. Be ready to kick it in before the PCs are well and truly screwed, so it's less obvious.
(It's actually more likely that you've underpowered it, and the players are going to nuke it faster than you expected. The fix for that is just "up the hit points on the fly", but also it's OK not to. Players feel good when they beat a scary enemy, and you can always take your lessons learned for future enemies.)
An important balancing concern is whether the players are going to come to this fight fresh or worn down by previous encounters.
From a rules perspective, a typical monster (up to CR 20) has
A monster that's higher in one area is typically lower in another, but there's a ton of noise in published stat blocks. A legendary monster should generally do about half of its damage budget on its turn, and the rest with legendary actions; other monsters typically do all their damage on their turn.
If you just follow those rules, you'll be similar in power to published monsters, so if you already know what CR of boss it takes to challenge your PCs (the DMG rules for that are, however, lousy) you can just design to the same benchmarks.
However, there's a separate issue: making a tactically interesting boss monster is a bit of an art, and published examples are not very good at it.
Some additional things to consider:
1. What is the action economy of your players? I.e, how many actions and bonus actions are they doing per round? Your monsters should be equivilant to that, either through multi attack, additional monsters, or legendary actions.
2. How much health do your players have, and how much of that do you want to be able to take out at a given time? I personally like to be able to deal at least 75% of a player’s max health in damage for a boss fight, forcing them to use healing resources. Numbers might change based on party dynamic, particularly if they do not have a dedicated healer.
3. What can the boss do to change the battlefield? A good boss is not static - they do things that might change the combat math and force folks to think on their toes.
This really isn't true. Actual number of actions only matters when there are abilities in play that add or subtract actions (if monster A has one action that does 100 damage, and monster B has two actions that do 50 damage, they both do 100 damage normally, but removing or adding an action from monster A matters a lot more than for monster B), otherwise all that matters is the effect of those actions.
That's definitely an issue of what your players actually consider challenging. I generally prefer to drop multiple PCs to zero hit points.
Offering clarification due to bad writing (yay, head colds!) on both points:
For the first point, I agree there are often better ways for balance. But looking at action economy is a very easy, concrete way to judge a party’s capabilities versus the boss, particularly when you are evaluating in light of things like generic attacks, which, even on high level monsters, are fairly low-powered in the individual. If using other monsters as a comparison or starting point, this is a good data point to keep in mind.
For the second point, I left out a pretty important part - the 75% damage was in a single round. Thus, while not likely to kill a player in round 1 (which is not great design since you might take them out before a response can be performed), you’re very likely to take someone out during a given boss fight, or at least put enough pressure that the party has to work in order to avoid that death.
My party is made up of three level fours; a paladin, a fighter, and a rogue. The paladin has 40 HP, the fighter has 42 HP, and the rogue has 39 HP. However, said rogue is also an idiot and decided to get drunk before the fight and, additionally, is on 29 HP at the moment due to trying to rob someone earlier.
Star Trek enthusiast, UTDR fan, Dean Winchester lover, and aspiring author/artist.
SPAMTON G. SPAMTON FOR [[present]]IDENT!