Whiteplume Coffin

Globe room

Have fun with air elemental blasting all globes. And having people struggle with the ring.
Give them a few spells to dispell darkness? It's super hard otherwise...
On the other hand 1v4 level 7s...
At least give them some healing here...
Protection from Evil and Good scroll!

Golem room

Prime puzzle (ez). Otherwise berserk golems.
5x CR5 flesh golems that start attacking each other at <=40HP.

Geysir and Chains

Rope! Learn timing of geysirs. Flesh golem? Named it?
No flight?

Vampire intro

Green torches light in pairs outside chamber. SFX
"My my my, what exquisite specimens."
"Did you come here all by yourself? Did you climb the rope? I hope no one fell.. It would've been a waste of a perfectly good heart."
"Well, I would pardon my manners, but it would appear you're the ones who walked into my bedroom."
"I am Ctenmiir. I can already tell we will be good friends.

Move around tap on shoulders.
"Aren't you a strong one? Goliath, yes?"
"An infernal. I sense much power in you."
"Ah, the a stealthy little gnome. Almost didn't see you there through your blinking trousers."

As he leans in behind you, his visage becomes visible briefly.

You see a pale and gaunt looking face, bone structure immediately reminds you of some of the finest soldiers you've seen. Short wavy black hair, dangling from his shoulders.
He wraps an arm around you and leans in to whisper,

"You're clearly the strongest one in the group. Why don't you protect me instead? This will much cleaner without the pointless bloodshed." DON’T ANSWER
As you see him whispering, you see a row of perfect white teeth. And as he finishes his sentences, you see him smile around the room and a large canine tooth is clearly visible.
Make a WIS save.

Coffin

CR13 vampire! In darkness! 3x Legendary resistance! Still easier than 2x efreeti...
20hp regen at start of turn out of sunlight.
Spider climb, weak to a few inconsequential things that they probably won't know.
Hint of vampirism?

Can charm with dc17. Remember to show self just a little.
No children of the night unless it's rough?
Might have to take out the round regen? It's pretty strong... But hard to tell how wounded the creature is...
Or leave everything as is and remove the darkness. Then play it adversarially.

Whelm

+3 warhammer for dwarves.
Fear of beind outdoors: disadv on attk/save/cheks while seeing day sky.
Thrown: 20/60 ft range. 1d8 extra bludg. Dmg or 2d8 extra vs giants. Return flight.
Shock wave: Strike ground. 60ft DC15 con save or 1min stun (round repeat). Once per day.
Awareness: gain knowledge of secret or concealed doors within 30ft of you. Can cast detect evil&good or locate object from weapon once per day.
Sentience: LN INT15 W12 CHA15. Darkvision+hearing 120ft.
Personality: Wants to slaughter giants + goblinoids. Conflicts if failing to do so.
Ties to Mightyhammer clan. But used by a Vampire to bend it to evil purposes killing own clan.
Maybe dwarven voice?

Tweaks: not dwarves only? +1 on start.
Take out awareness.
Takes out shock wave.

Awakened: +2
Add shock wave
+4 str

Levels up by killing giants.

Lines

Arr. Yar a big one aren't ya. Be ye Giant, or large human?
Well, it matters. How effective do you expect me to be when I know your kind murdered my ancestors?
Are you willing to lay down your life to vanquish evil?

Are you willing to walk the path of righteousness and eliminate every giant and vampire that stands in our way?
If so, you'll see me fly into the faces of evil, and return to your hand on command.
I'll grant you awareness, and powerful capabilities. But only if you work to further our noble goals.

Personality (as per original)

Whelm’s purpose is to slaughter giants and goblinoids. It also seeks to protect dwarves against all enemies. Conflict arises if the wielder fails to destroy goblins and giants or to protect dwarves.

Whelm has ties to the dwarf clan that created it, variously called the Dankil or the Mightyhammer clan. It longs to be returned to that clan. It would do anything to protect those dwarves from harm.

The hammer also carries a secret shame. Centuries ago, a dwarf named Ctenmiir wielded it valiantly for a time. But Ctenmiir was turned into a [monster]vampire[/monster]. His will was strong enough that he bent Whelm to his evil purposes, even killing members of his own clan.