Regeneration. The revenant regains 10 Hit Points at the start of its turn. If it took Fire or Radiant damage, this doesn't work at the start of its next turn. Its body is destroyed only if it starts its turn at 0 Hit Points and doesn't regenerate.
Undead Restoration. Killed, it rises again a day later in another corpse unless Dispel Evil and Good is cast on the body.
Actions
Multiattack. Vengeful Glare and two Slams.
Slam. A blow of cold, undying fury.
Vengeful Glare.DC 15 Wis save by a creature within 30 ft or Frightened for a minute (saving at the end of its turns); its sworn foe is Paralyzed too.
Bonus actions
Vow of Revenge. Once a day: curses a creature within 30 ft as its sworn foe, always knowing where it is.
Where you meet it
Argynvostholt: The men-at-arms come out of the courtyard in their grey ranks, still fighting the last battle, and turn…
The Beacon Tower: Vladimir comes off the last step with his greatsword already moving. Behind him on the stair, dead knights in…
Argynvostholt, Ground Floor: Vladimir rises from the winged chair for the first time, and all down the table dead heads turn to watch. He…
Castle Ravenloft, Strahd's Tomb: Vladimir draws, and his knights come down the black stair behind him with their swords already out.