Follow-up on my post above: My players dispatched the Atropal in three rounds, but it was fairly tense. The cleric cast Dawn, which amounts to ongoing radiant damage, which sped things up, and that was fine. The Atropal was doing its best to target the cleric and force concentration checks, but didn't really succeed; that said, I was reasonably happy at how the encounter went.
Acererak was another issue--not because he had the party outclassed, but because his spell list did not match the encounter and terrain. Here's his spell list from the stat block:
Cantrips (at will): mage hand, ray of frost, shocking grasp
1st level (at will): ray of sickness, shield
2nd level (at will): arcane lock, knock
3rd level (at will): animate dead, counterspell
4th level (3 slots): blight, ice storm, phantasmal killer
5th level (3 slots): cloudkill, hold monster, wall of force
6th level (3 slots): chain lightning, circle of death, disintegrate
7th level (3 slots): finger of death, plane shift, teleport
8th level (2 slots): maze, mind blank
9th level (2 slots): power word kill, time stop.
I put in time preparing for the encounter, as this was my first high-level wizard NPC, and as the party also has a wizard, it would turn out to be a bit of a wizarding duel. I came up with my 'action order' list, divided by whether he would be attacking multiple targets, or just one. Here's my list:
Multiple targets - Chain Lightning (6+); Circle of Death (6+), Cloudkill (5+), Ice Storm (4+);
One target: Maze (Troll); Power Word Kill (9), Finger of Death (7); Disintegrage (6+); Phantasmal Killer (4+); Hold Monster(s-5+); Blight (4+)
Melee: Staff attack; Paralyzing Touch
Here are the problems, and my recommendations for fixing them:
1) Mobility - As written, Acererak has no way to get around, other than to waste a seventh-level spell slot on Teleport. Looking at the available teleportation spells, I would probably add Thunder Step as 3rd-level at-will spell. Its 90-foot range is enough to get around this chamber, and it deals damage to everyone within 10 feet of the spot you just left.
2) Dispel Magic - As mentioned in a previous post, Acererak absolutely needs Dispel Magic. He has to be able to get rid of the PC caster's spell effects, also as a 3rd-level at-will.
3) Silence - As written, if the party casts Silence, Acererak has no way of dealing with it. Even if you add a teleportation spell, all of these have a verbal component, so if he is on one of the platforms, he has no way to escape the area of the spell. He has enough attacks to deal with anyone in melee (especially if he can paralyze them), but would not be able to do a thing about spells cast from range. One solution could be for him to drink a potion of flying prior to combat, which would give him a fly speed without requiring concentration (this would also address #1 above...)
4) Lava - The lava is a real threat with the Atropal, but once Acererak arrives and the PCs have 50 temp HP per round from the trickster gods, the average of 55 per round they get in the lava doesn't seem to scary--unless Acererak is also targeting them with spells. Just something to keep in mind.
NOTE: Only in the course of writing this did I come acrosse Sly Flourish's analysis of Acererak's spell list at:
Note: This article contains spoilers for the D&D adventure Tomb of Annihilation. This article is one in a series of artices I wrote for running the D&D hardcover adventure Tomb of Annihilation. You ca...
slyflourish.com
Wish I had seen this beforehand. The only change I would make to his list would be the addition of Thunder Step--and probably that potion of flying.