Zograthil, the Chained God

Legendary Resistance (4/Day). If Zograthil fails a saving throw, it can choose to succeed instead.

Godly Presence.  At the start of their turn, any creature that can see Zograthil must make a DC 17 Wisdom saving throw. On a failed save, they take 3d10 psychic damage, half on a successful save.

Turn Immunity. Zograthil has immunity against any effect that turns undead.

Undead Fortitude. If damage reduces Zograthil to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, Zograthil drops to 1 hit point instead.

Multiattack. Make two Bash attacks.

Call of the Grave. Target a dead creature that you can see within 60ft. of you. You speak words of undeath, and raise the corpse as an Undead creature under your control. The creature takes its turn immediately after yours.

Grapple. Melee Unarmed Attack: +11 to hit, reach 20 ft., 1 target. Hit: The target must make a DC 20 Dexterity or Strength saving throw. On a failed save, the creature is grappled.

Bash. Melee Unarmed Attack: +14 to hit, reach 20 ft., 1 target. Hit: 36 (4d10 + 13) bludgeoning damage and 36 (8d8) necrotic damage.

Chain Whip. Ranged Unarmed Attack: +11 to hit, reach 30 ft., 1 target. Hit:  35 (4d10 + 11) bludgeoning damage. On a hit, the target must make a DC 20 Dexterity saving throw. On a failed save, they are grappled. The creature may repeat this saving throw at the end of their turns.

Zograthil can take 4 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. Zograthil regains spent legendary actions at the start of its turn.

Bash (Costs 1 Action). Make a Bash attack against a creature.

Grapple (Costs 1 Action). Make a grapple check against  a creature within your melee attack range.

Death Grip (Costs 2 Actions). A creature of your choice you have grappled takes 8d8 necrotic damage.

Abyssal Shriek (Costs 4 Actions). Any creature within 60ft that can hear you makes a Wisdom saving throw. On a failed save, affected creatures are knocked prone and take 3d10 psychic damage, on a success, they take half damage and are not knocked prone.