Aldrich, Devourer of Gods

Blessing of the Deep. Aldrich can breathe air and water.

Legendary Resistance (3/Day). If Aldrich fails a saving throw, it can choose to succeed instead.

Spellcasting. Aldrich, Devourer of Gods is a 20th-level spellcaster. His spellcasting ability is Wisdom (spell save DC 20, +13 to hit with spell attacks). Aldrich has the following spells prepared, which are considered 
Cantrips (at will): light, thaumaturgy, toll the dead, word of radiance
1st level (at will): bane, guiding bolt, inflict wounds, magic missile
2nd level (at will): gentle repose, silence, spiritual weapon (as a scythe)
3rd level (at will): bestow curse, dispel magic, speak with dead
4th level (4 slots): banishment, control water, freedom of movement
5th level (3 slots): contagion, flame strike, holy weapon
6th level (3 slots): create undead, harm, word of recall
7th level (3 slots): fire storm, regenerate
8th level (2 slots): feeblemind, mind blank
9th level (2 slots): weird

Impersonation. As a bonus action, Aldrich can extrude a piece of itself that assumes the appearance of one Medium or smaller creature whose memories it has stolen. This simulacrum appears, feels, and sounds exactly like the creature he impersonates, though it smells faintly of rotting flesh. Aldrich can impersonate 2d6 + 1 different creatures, each one tethered to its body by a strand of slime that can extend up to 120 feet away. For all practical purposes, the simulacrum is Aldrich, meaning he occupies his space and the simulacrum’s space simultaneously. The slimy tether is immune to damage, but it is severed if there is no opening at least 1 inch wide between Aldrich's main body and the simulacrum. The simulacrum disappears if the tether is severed.

Multiattack.  Aldrich makes two attacks with his Darkmoon Longbow, or makes two attacks with Lifehunt Scythe, a spectral scythe he can conjure. 

Darkmoon Longbow. Ranged Weapon Attack: +11 to hit, range 150/600 ft., 1 target. Hit: 12 (1d8 + 7) piercing damage, plus 18 (4d8) radiant damage. 

Lifehunt Scythe. Melee Spell Attack: +11 to hit, reach 10 ft., 1 target. Hit: 11 (2d4 + 6) slashing damage, plus 18 (4d8) necrotic damage. Aldrich recovers hit points equal to any damage he deals with this attack.

Devour. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 45 (10d8) acid damage. The target is devoured and reduced to a skeleton within Aldrich's mass if this damage leaves the creature with 0 hit points. Aldrich inherits the memories of any creature it has devoured. 

Rain of Arrows. A storm of divine arrows rains down from the heavens. All creatures in a 20 ft. radius must make a Dexterity saving throw (DC 20) the first time they enter the radius or when they start their turn in it. On failure, they take 12 (1d8 + 7) piercing damage, plus 18 (4d8) radiant damage. This effect persists until the end of Aldrich's next turn. 

Aldrich, Devourer of Gods 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. Aldrich regains spent legendary actions at the start of his turn. 

Lifehunt Scythe. (Costs 1 Action). Aldrich makes one attack with Lifehunt Scythe. 

Rain of Arrows. (Costs 1 Action). Aldrich repositions an active Rain of Arrows effect. 

Deep Submersion. (Costs 2 Actions). Aldrich submerges himself into the depths. All creatures within 5 feet of Aldrich must make a Dexterity saving throw (DC 20) or take 14 (3d8) acid damage. Aldrich then reappears within 30 feet in a nearby location. Aldrich and the target location must be in water or slime.