Azathoth

Legendary Resistance. If Azathoth fails a saving throw, it chooses to succeed instead.

The Blind God. Every roll Azathoth makes has doubled advantage (roll 3 take highest). When Azathoth is reduced to 0 HP, it Wakes.

Colossal. If Azathoth enters the space of any creature that is not Grappling it, the creature takes 5d20 force damage (DC 30 STR save, half damage on save)

Multiattack. Azathoth uses its Frightful Presence, makes as many Void attacks as possible, then uses Natural Defenses if there are less than 3 Eldritch Beasts remaining.

Frightful Presence. All creatures and aware of Azathoth must succeed on a DC 25 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if Azathoth is within line of sight, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Azathoth's Frightful Presence for the next hour.

Void. Azathoth traps one creature whose space it is occupying, then shunts it into the Eternal Void (DC 30 WIS save) where it takes 200d10+45 damage per turn until it succesfully makes a DC 30 WIS save to escape

Natural Defenses. 1d6 Eldritch Beasts (roll a d12 on a table of possible monsters) spawn on Azathoth's surface.

WAKE. Activates upon Azathoth being reduced to 0 or less HP. Azathoth Wakes, and with it, the dream of the universe ends. Every being everywhere must make a DC 5000 Will save. Upon failing, they take ∞ damage. Azathoth will only dream again if he is Wish spelled to sleep thrice, then once a day, every day thereafter. Should Azathoth be put to sleep again, he is considered dead and will no longer attack.

Azathoth 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. Azathoth regains spent legendary actions at the start of its turn.

Void. Azathoth uses Void as many times as possible.