Vai is a vampire who’s lair could exist in just about an any underground environment. The lair is protected by a secret passage, a trapped false entrance, and a few unique monsters. You could place this anywhere in an existing game.
The entrance is a large bronze door, with a skull fixed high in the center. The eyes of the skull glow like smoldering coals. A large flat stone sits before the door. This stone shows traces of blood on closer inspection.
The skull addresses visitors with:
“A tribute in blood to the dark lord, or flee for you are mere sheep at the den of the King of wolves”
Spilling blood on the stone will satisfy the skull. This can be a sacrifice, or a character can cut themselves spilling their own blood (a poor sacrifice but, meets the requirements).
If the sacrifice is earnestly given the skull opens the door, and the secret door. If the skull deems the sacrifice weak the skull opens the front door only.
Trying to bypass the door in any other way causes the skull/door to attack the would be interlopers.
Treat the skull as a flameskull with the limitation that it is fixed to the door, AC 10. Others as per the description in the Monster Manual.
The entrance hall
This hall leads to an octagonal room. The secret door, if not opened by the skull can be found with a DC 15.
The false entrance
This is an octagonal room with a symbol of chaos engraved in the stone floor. Seven doors surround the room, each is made of bronze with faces of women cast in the surface. While the center door has a crown set high in the center.
The three doors on each side are locked, and trapped. Attempting to open any of these doors causes a crossbow bolt to fire from the mouth of one of the faces. On the next round bolts fire from the remaining doors. After one round the process repeats for another 1d6 rounds.
Trap DC 13. Each door needs to be disarmed with a separate check. Crossbow bolt +4 melee 5 (1d8+1).
The doors are all locked DC 17. Behind each door is a small room with a skeleton who fires the crossbow and reloads.
The center door is unlocked. Behind this door is an inky black cloud that slowly flows into the room engulfing the characters.
The haunting miasma appears as a thick black cloud. The cloud flows in a roiling inky blackness. It can flow through small gaps or spaces.
The Haunting Miasma occupies up to 4 adjacent squares.
The haunting miasma flows into the same square occupied by a character to attack engulfing the character. Squares engulfed by the haunting miasma are in darkness, like the spell. Characters engulfed are subject to an engulfing attack which does not require a roll to hit.
Armor Class: 8
Hit Points: 22 (5d8)
Speed: fly 15ft.
Damage Resistances: acid, cold, fire, lightning, thunder; bludgeoning, piercing, and slashing from nonmagical weapons Damage
Immunities: necrotic, poison
Susceptibility: Effects that generate a strong wind do 2d6 to the miasma.
Condition Immunities: charmed, exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious
Senses: darkvision 60 ft., passive Perception 10
Life Drain special Spell Attack:
Any engulfed creature: 10 (3d6) necrotic damage. The target must succeed on a DC 10 Constitution saving throw or its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the creature finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.
Vai’s throne room
A stone throne sits atop ten foot platform. Two short stairs lead up to the platform. Behind the throne is an arched portal with a shimmering violet and black wall, like shifting magical curtain.
Either Vai is in this chamber, if you want to fight a vampire, or Vai is long dead and the characters have found the lair he has left behind.
The black prismatic wall
The black prismatic wall looks like an ever shifting, and shimmering wall with an oily black presence. The wall is opaque for the most part, with shifting images of a bleak and barren landscape, visible intermittently.
The the black prismatic wall is a portal that passes through the plane of shadow. Undead creatures pass through the wall with no trouble. Living creatures passing through the wall take 4d8 necrotic damage, and must make a DC 14 Con save or have their maximum hit points reduced by the amount of damage taken. The reduction lasts until the character finishes a long rest. Passing through the wall also requires a DC 13 Wis. check. On a failure the character is lost on the plane of shadow, and takes the necrotic damage effect listed above again, and must make another Wis. check. On a successful Wis. check the character passes through to the other side of the wall.
A Daylight spell cast on the wall eliminates the effect of the wall while the spell is in effect. allowing characters to freely pass.
Passing through the wall characters find themselves in Vais’ sleeping chamber.
Vai’s Sleeping Chamber
Beyond the wall is Vai’s sleeping chamber, a stone coffin. This room could be the final battle with Vai, or the other encounters could have been enough, and this could contain a sought after treasure.
I left a few open ends so you can fit this into their own games. Vampires in 5e are pretty tough (CR13)! Including a vampire would make the first three encounters easy. For lower level parties, the first encounters could be pretty challenging, and a vampire would be too much.
The Skull Door is based on the Flameskull with a lower AC. This would be about CR 3 or 4 (watch out for that Fireball). This encounter can also be bypassed with careful role-play.
The crossbow trap. Could be a minor annoyance. You could make this tougher by ruling that all 6 doors fire at the same time. I like to have a mechanism for traps. In this case skeletons firing crossbows. Using skeletons here you can rule that they fire as often as once per round.
I understand that “prismatic” and “black” are a little at odds. I chose to call this a prismatic wall as a nod to Dave Hargrave’s Arduin Grimoire Volume 1. This book lists series of “Prismatic Walls” of many different colors, each with a different effect. I gave my wall an effect different from Arduin Prismatic walls, which always had the effect of not allowing certain things to pass them.
The Prismatic wall can be pretty hard on a lower or upper level party. The damage dealt can be adjusted for your party level. Note that the room on the other side is not visible through the wall. This makes for interesting thought process by the players. After the first player enters the room, the others won’t be able to see what is happening.
I chose the name Vai, from Steve Vai who I always thought would make a good vampire. He also has an uncanny resemblance to the Vampire in Heart of Nightfang Spire.This also fits with the Rock Cosmology.