Vassalich (5e Creature)

Medium undead, any evil alignment

Armor Class 16 (natural armor)
Hit Points 65 (10d8 + 20)
Speed 30 ft.

Saving Throws Con +5, Wis +3
Skills Arcana +9, Perception +3
Proficiency Bonus +3
Damage Resistances cold, lightning, necrotic; bludgeoning, piercing and slashing from nonmagical attacks
Damage Immunities poison
Condition Immunities charmed, exhaustion, frightened, paralyzed, poisoned
Senses darkvision 60 ft., passive Perception 13
Languages Common plus three other languages
Challenge 7 (2,900 XP)

Rejuvenation. A destroyed vassalich gains a new body in 2d10 days, regaining all its hit points, unless its phylactery is found and destroyed. The new body appears within 5 feet of the phylactery.

Spellcasting. The vassalich is an 9th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 15, +7 to hit with spell attacks). The vassalich has the following wizard spells prepared:

Cantrips (at will): mage hand, prestidigitation, ray of frost
1st level (4 slots): detect magic, false life, shield
2nd level (3 slots): detect thoughts, invisibility, mirror image, see invisibility
3rd level (3 slots): clairvoyance, dispel magic, fireball, stinking cloud
4th level (2 slots): confusion, dimension door
5th level (1 slot): dominate person

A vassalich, sometimes mockingly called a lesser lich or junior lich, is a mortal turned into a undead spellcaster by a true lich. The vassalich serves as a minion and apprentice to the true lich in return for the immortality of undeath. Like the true lich, the vassalich has its own phylactery.

Undead Nature. A vassalich doesn't require air, food, drink, or sleep.