Legendary Resistance (3/Day). If Arcturia 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. Arcturia has advantage on saving throws against any effect that turns undead.

Spellcasting. Arcturia is an 18th-level spellcaster. Her spellcasting ability is Intelligence (spell save DC 20, +12 to hit with spell attacks). Arcturia can cast alter self at will and 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): detect thoughts, enlarge/reduce, Melf's acid arrow, mirror image

3rd level (3 slots): counterspell, dispel magic, fireball, slow

4th level (3 slots): blight, polymorph

5th level (3 slots): animate objects, telekinesis

6th level (1 slot): disintegrate, flesh to stone

7th level (1 slot): reverse gravity, teleport

8th level (1 slot): feeblemind, maze

9th level (1 slot): true polymorph

Paralyzing Touch. Melee Spell Attack: +12 to hit, reach 5 ft., one creature. Hit:10 (3d6) cold damage. The target must succeed on a DC 18 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Cantrip. Arcturia casts a cantrip.

Paralyzing Touch (Costs 2 Actions). Arcturia uses its Paralyzing Touch.

Frightening Gaze (Costs 2 Actions). Arcturia 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 Arcturia 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.