Divine Will (4/Day). If the lich fails a saving throw, it can choose to succeed instead.

Unusual Nature. The lich doesn’t need air, food, drink, or sleep.

Multiattack. The lich makes one Parasitic Tentacle attack or uses Spellcasting. Zuxin also uses Psychic Whisper twice.

Parasitic Tentacle. Melee Weapon Attack: +9 to hit, reach 10 ft., one creature. Hit: 25 (10d6 + 4) piercing damage plus 25 (6d6 + 4) necrotic damage. The target must succeed on a DC 17 Constitution saving throw or be poisoned. The poisoned target can repeat the save at the end of each of its turns, ending the effect on itself on a success. The third time the target fails the save, the target dies and dissolves into a gibbering mouther that obeys the lich and uses the target’s initiative.

Psychic Whisper. The lich targets one creature it can see within 120 feet of itself. The target must succeed on a DC 20 Wisdom saving throw or take 25 (6d8 + 4) psychic damage and be stunned until the end of the lich’s next turn as insane whispers fill the target’s mind.

Spellcasting. The lich casts one of the following spells, using Intelligence as the spellcasting ability (spell save DC 17):

At will: detect magic, mage hand, prestidigitation, eldritch blast (as level 17)

2/day each: dispel magic, hunger of Hadar, lightning bolt (as a 9th slot)

1/day each: arcane eye, dimension door, plane shift (self only)

Far Realm Step. Immediately after taking damage, the lich, along with any equipment it is wearing or carrying, magically teleports up to 60 feet to an unoccupied space it can see.

Divine Oppression (3/Day). Zuxin reaches out with his consciousness and takes hold of a creature's mind within 120 feet.  Creatures must pass a DC20 Wisdom saving throw to resist Zuxin's oppression or receive the Charmed status for one minute.  At the start of each of its turns, the oppressed creature can make a DC20 Wisdom check to shake off Zuxin's oppression and regain control of its mind and body.

Divine Possession (1/Day). Upon reaching 0 HP, Zuxin severs his soul's connection with the eldritch lich and possesses the creature closest to it and restores its HP to full.  The creature's soul is annihilated unless it possesses the Divine Intervention feat.