Magic Resistance. Xaczyis has advantage on saving throws against spells and other magical effects.

Innate Spellcasting (Psionics). Xaczyis innate spellcasting ability is Intelligence (spell save DC 15). It can innately cast the following spells, requiring no components:

At will: detect thoughts, levitate

1/day each: dominate monster

Amphibious

this creature can breathe water and air

Divine rebirth 

after the creature has been killed outright it returns to quarter of max hp after 2d4 rounds, it cannot be destroyed unless the belief in it is destroyed too, or to a sufficient quantity that it can not be remade

Tentacles. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 15 (2d10 + 4) psychic damage. If the target is Medium or smaller, it is grappled (escape DC 15) and must succeed on a DC 15 Intelligence saving throw or be stunned until this grapple ends.

Divine Blast (Recharge 5–6).  Xaczyis magically emits divinely made psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 15 Intelligence saving throw or take 22 (4d8 + 4) psychic damage and be stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.