20 (natural armor)
80 (20d4)
walk 0 ft., fly 30 ft.
Con +6, Int +11, Wis +9, Cha +11
bludgeoning, piercing, slashing from magic weapons
necrotic, poison, psychic; bludgeoning, piercing, slashing from nonmagical attacks
charmed, deafened, exhaustion, frightened, paralyzed, petrified, poisoned, prone, stunned
truesight 120 ft.
18
If the demilich is subjected to an effect that allows it to make a saving throw to take only half damage, it instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.
If the demilich fails a saving throw, it can choose to succeed instead.
The demilich is immune to effects that turn undead.
The demilich emits a bloodcurdling howl. Each creature within 30 feet of the demilich that can hear the howl must succeed on a DC 15 Constitution saving throw or drop to 0 hit points. On a successful save, the creature is frightened until the end of its next turn.
The demilich targets up to three creatures that it can see within 10 feet of it. Each target must succeed on a DC 19 Constitution saving throw or take 21 (6d6) necrotic damage, and the demilich regains hit points equal to the total damage dealt to all targets.
The transformation into a demilich isn't a bitter end for all liches that experience it. Made as a conscious choice, the path of the demilich becomes the next step in a dark evolution. The lich Acererak—a powerful wizard and demonologist and the infamous master of the Tomb of Horrors—anticipated his own transformation, preparing for it by setting enchanted gemstones into his skull's eye sockets and teeth. Each of these soul gems possessed the power to capture the souls on which his phylactery would feed. Acererak abandoned his physical body, accepting that it would molder and dissolve to dust while he traveled the planes as a disembodied consciousness. If the skull that was his last physical remains was ever disturbed, its gems would claim the souls of the insolent intruders to his tomb, magically transferring them to his phylactery. Liches who follow Acererak's path believe that by becoming free of their bodies, they can continue their quest for power beyond the mortal world. As their patron did, they secure their remains within well-guarded vaults, using soul gems to maintain their phylacteries and destroy the adventurers who disturb their lairs. Acererak or another demilich like him has a challenge rating of 21 (33,000 XP), or 23 (50,000 XP) in its lair, and gains the following additional action option. Trap Soul: The demilich targets one creature that it can see within 30 feet of it. The target must make a DC 19 Charisma saving throw. On a failed save, the target's soul is magically trapped inside one of the demilich's gems. While the soul is trapped, the target's body and all the equipment it is carrying cease to exist. On a successful save, the target takes 24 (7d6) necrotic damage, and if this damage reduces the target to 0 hit points, its soul is trapped as if it failed the saving throw. A soul trapped in a gem for 24 hours is devoured and ceases to exist. If the demilich drops to 0 hit points, it is destroyed and turns to powder, leaving behind its gems. Crushing a gem releases any soul trapped within, at which point the target's body re-forms in an unoccupied space nearest to the gem and in the same state as when it was trapped.
The undead can take 4 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The undead regains spent legendary actions at the start of its turn.
The demilich flies up to half its flying speed.
The demilich magically swirls its dusty remains. Each creature within 10 feet of the demilich, including around a corner, must succeed on a DC 15 Constitution saving throw or be blinded until the end of the demilich's next turn. A creature that succeeds on the saving throw is immune to this effect until the end of the demilich's next turn.
Each creature with in 30 feet of the demilich must make a DC 15 Constitution saving throw. On a failed save, the creature's hit point maximum is magically reduced by 10 (3d6). If a creature's hit point maximum is reduced to 0 by this effect, the creature dies. A creature's hit point maximum can be restored with the greater restoration spell or similar magic.
The demilich targets one creature it can see within 30 feet of it. The target must succeed on a DC 15 Wisdom saving throw or be magically cursed. Until the curse ends, the target has disadvantage on attack rolls and saving throws. The target can repeat the saving throw at the end of each of its turns, ending the curse on a success.
On initiative count 20 (losing initiative ties), the demilich rolls a d20. On a result of 11 or higher, the demilich takes a lair action to cause one of the following effects. It can't use the same effect two rounds in a row. • The tomb trembles violently for a moment. Each creature on the floor of the tomb must succeed on a DC 19 Dexterity saving throw or be knocked prone. • The demilich targets one creature it can see within 60 feet of it. An antimagic field fills the space of the target, moving with it until initiative count 20 on the next round. • The demilich targets any number of creatures it can see within 30 feet of it. No target can regain hit points until initiative count 20 on the next round.
A demilich's tomb might have any or all of the following effects in place: • The first time a non-evil creature enters the tomb's area, the creature takes 16 (3d10) necrotic damage. • Monsters in the tomb have advantage on saving throws against being charmed or frightened, and against features that turn undead. • The tomb is warded against the magical travel of creatures the demilich hasn't authorized. Such creatures can't teleport into or out of the tomb's area or use planar travel to enter or leave it. Effects that allow teleportation or planar travel work within the tomb as long as they aren't used to leave or enter the tomb's area. If the demilich is destroyed, these effects fade over the course of 10 days.