The lich is an 18th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 22, +16 to hit with spell attacks). The lich has the following wizard spells prepared: Cantrips (at will): mage hand, prestidigitation, ray of frost 1st level (4 slots): detect magic, magic missile, shield, thunderwave 2nd level (3 slots): acid arrow, detect thoughts, invisibility, mirror image 3rd level (3 slots): animate dead, counterspell, dispel magic, fireball 4th level (3 slots): blight, dimension door 5th level (3 slots): cloudkill, scrying 6th level (1 slot): disintegrate, globe of invulnerability 7th level (1 slot): finger of death, plane shift 8th level (1 slot): dominate monster, power word stun 9th level (1 slot): power word kill
Legendary Resistance (3/Day). If the lich fails a saving throw, it can choose to succeed instead. Rejuvenation. If it has a phylactery, a destroyed lich gains a new body in 1d10 days, regaining all its hit points and becoming active again. The new body appears within 5 feet of the phylactery. Turn Resistance. The lich has advantage on saving throws against any effect that turns undead.
The lich can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The lich regains spent legendary actions at the start of its turn. Cantrip. The lich casts a cantrip. Paralyzing Touch (Costs 2 Actions). The lich uses its Paralyzing Touch. Frightening Gaze (Costs 2 Actions). The lich fixes its gaze on one creature it can see within 10 feet of it. The target must succeed on a DC 18 Wisdom saving throw against this magic or become frightened for 1 minute. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target’s saving throw is successful or the effect ends for it, the target is immune to the lich’s gaze for the next 24 hours. Disrupt Life (Costs 3 Actions). Each non-undead creature within 20 feet of the lich must make a DC 18 Constitution saving throw against this magic, taking 21 (6d6) necrotic damage on a failed save, or half as much damage on a successful one.
Will rely on glyphs set up all over his tower with the following spells (Cloudkill + Wall of Force) (Counterspell to go off on 5th level or higher spells) (Feeblemind Glyphs) (Protective Counterspells for Feeblemind) (Planeshift Glyphs) Shield Guardians guard the lich Iron Golems will also guard the lich