Balancing my boss encounter [closed]

Question

I am planning my first GM story for a group of 7 friends and I am preparing a possible boss encounter as the climax of the story. I could use your help balancing the encounter so that it is deadly, but not impossible for the party to defeat.

It should be noted that I have created a non-combat way for the players to seal it in some catacombs forever, this is just in case they decide to try and kill the boss instead.

Group: 7 players level 3 or 4. None of the characters have been created at this moment.

Boss encounter: I am thinking of making the boss (Referred to as "the bane") a Death Slaad (Monster manual p. 278), but it seems that it might be too strong. Also I would like to add maybe one or two skeleton minotaurs (Monster Manual p. 272).

As the encounter stands at the moment I have no doubt that the encounter is too strong.

Adjustments considered: I have thought of removing the Death Slaad's necrotic damage (2d6), which it has to all its attacks, to make sure that it wont one shot the PCs.

Any advice and suggestions is greatly appreciated.

Answer 1

Basic Encounter Analysis

So, you have a party of 7 players of (just to pick a number) level 4.

Versus a Death Slaad (CR 10, worth 5,900 XP) and up to a pair of Minotaur Skeletons (CR 2, worth 450 XP each). Added together, your large-end encounter has a base XP budget of 6800 XP. Considering that you're up against 3 monsters, and have a party size greater than six...you're dealing with a 1.5x modifier on that budget. The effective encounter difficulty is set at 10,200 XP.

For 7 4th level players, the threshold for a 'Deadly' encounter is 3,500 XP.

Your players are up against an encounter that is nearly 3x as difficult as what would be considered a 'Difficult' encounter. They are going to get slaughtered unless they are exceptionally clever.

On the other hand...if you ditch the Minotaurs and only put them up against the Slaad. You have a base encounter budget of 5900 XP. Given that it's 7 players vs 1 monster, the multiplier on that is 0.5x. The effective difficulty there is 2950. Technically: a 'Hard' fight, but not 'Deadly.'

Vs a Death Slaad alone

But, then you have to take into consideration the capabilities of a Death Slaad.

An 'Average' tanky melee character of 4th level has around 33-40 hit points.

A Death Slaad has access to two castings of Fireball (average of 24 damage per hit) and a single casting of Cloudkill (average of 20 damage per hit, potentially ongoing). Additionally, if it hits with all three of its weapon attacks, you're looking at an average of 54 damage.

In short...if the Death Slaad goes all out on the party, it can likely kill them all within 2-3 rounds. Open with Cloudkill, then Fireball, Fireball, mop up any survivors with melee attacks.

On top of this, it has armor equivalent with full plate, and 170 hp + (effectively) 10, for every round it continues to survive, advantage on spell saves, and resistance to most types of elemental damage. 4th level players don't even have their Multiattack yet. The heaviest hitting spell they could throw at it (scorching ray) only hits for 6d6 damage (halved against the Slaad)...and that's IF all 3 bolts hit. A typical, well-optimized melee combatant hits for an average of about 15 damage at 4th level when they are going at it hard (burning class features to hit harder). And, again, this is against an AC of 18.

Unmodified, your players will probably win, but some of them will die in the process.

Solution A: Rebalance

I wouldn't throw a full-blown Death Slaad at them. To modify a Death Slaad to be less lethal, you'd have to do a lot of work.

What would be much easier is to take a weaker variety of Slaad and reskin it as a 'Lesser Death Slaad.' Drop the tadpole infection and replace it with a bit of necrotic damage. Give it a few spells...voila, Lesser Death Slaad.

And if you're worried about the encounter being 'too easy,' then you always have the old DM emergency fallback to rely on: Lie. I don't recommend doing this often, and doing it at all is a somewhat contentious topic among some DMs and Players. But I have personally found that it can help cover for a newer DM who just honestly doesn't know enough about the monsters they are running to build an appropriately balanced encounter. But you don't have to tell your players how many HP the enemy boss has left. If they are easily burning your monster down, just quietly boost its HP so that it lives to fight them longer.

Solution B: Make figuring out how to fight this thing an Adventure

Instead of throwing down with the Slaad directly, make an adventure of the party figuring out how to circumvent the fact that this thing will absolutely kick their teeth in if they fight it head on.

A few options...

1. On MM274, look at the Variant block on Slaad Control Stones. Make an adventure of finding a way to get your hands on (read: steal) this Slaad's stone so that they can control it.
2. Same principal as #1, but the party seeks out a magical artifact that can trigger a disruption to a Slaadi Control Stone, dramatically weakening their foe.
3. Add a method, acquired by quest, by which the players can seize control of the Minotaur Skeletons. This gives them some nice durable bone shields they can use in the fight against the Slaad.
4. Heavy Weapons/Ambush: Lure the Slaad and its minions into an ambush...perhaps with a battery of Siege weapons waiting for it.
5. Provide a way to banish it. Make the combat more about surviving the thing long enough for the banishment to work, rather than directly trying to kill it.

And so on. The goal here is that the party is faced with an 'insurmountably powerful foe' that they couldn't realistically fight until they were significantly stronger. But...tough. They have to stop it now, and that means they're going to have to figure out how to do it without a straight-up fight.

Answer 2

A single monster with CR 10 is meant to be challenged by 4 level 10 characters! Adding in any more monsters at all will seriously increase the CR of the encounter.

7 level 3 characters will find a challenge Deadly if the encounter XP is >= 2800 and Hard if the encounter XP is >= 1575.

7 level 4 characters will find a challenge Deadly if the encounter XP is >= 3500 and Hard if the encounter XP is >= 2625.

Using this handy encounter builder:

• By itself, a Death Slaad has an XP of 5900, adjusted for 7 characters gives you a 2950 encounter XP.
• Adding 1 Skeleton Minotaur, bumps this back up to 6350 (adjusted).
• Adding 2 Skeleton Minotaurs puts this at 10200 (adjusted)!

So I think you might be able to run the Slaad by itself against 7 level 4 characters. By the book they might win, but there is a high chance of at least one character dying, maybe even a TPK. They only stand a chance because of their sheer number. Adding in minions on the boss's side negates their only "advantage." Also note that if your characters have above-average stats or equipment they might stand a better chance.

If you want to run the Slaad as is with support, consider sending the characters on a quest for an artifact that will negate the Slaad's regeneration (don't just nerf it, make a story out of it!). Maybe another quest to find magic weapons or to penetrate the Slaad's Magic Resistance or elemental resistances (or leave them be and let the martial types shine in this fight) as well. Maybe they can talk another group into going in first and using up one of the Slaad's fireballs.