Apophis Scourge of the Universe

Immortal organs: Apophis has no need for organs, air, food, water, or other mortal means despite not being divine.

Blessing for the God eater: Apophis automatically succeeds on any saving throw as if god's favor him more then anything else.

Impervious. Any attack made on Apophis's scales or anywhere outside his body is immediately nullified but many mannerisms of magic and toughness the only way to bypass this is to deal 1000 damage in a singular turn. 

Multi-attack. Apophis may make twelve scale arrow attacks and one mountain breaker attack

Scale Arrow. Apophis's Massive scales powered by magic seek out any creature nearby hitting no matter what, if the target is obstructed the scale will hit the obstruction, A singular scale deals (10d10+40) slashing damage.

Mountain Breaker. Apophis with one claw hits the ground with the force of hundreds of supernovas instantaneously dealing (20d100+300) force damage to anything within a 2000ft radius of the hit.

World Eater. Apophis takes a bit out of the planets crust and into the mantle anything within the area is immediately eaten and anything outside will take (13d50+60) force damage from the pure impact with the planet 

Reactive Supernova. Apophis snaps his jaw with enough force to break light and atoms creating hundreds of Supernovas worth of energy which he then shoots as a beam instantly destroying anything in it's path in 1000 ft, anything living caught in the beam is incinerated to it's very soul.

Apophis may make any 9th level spell from all tables, he may only do this three times per day

Spells: Time Stop, Power word kill, Power word heal, Meteor Swarm, Foresight, Gate, Imprisonment, Mass heal, Prismatic wall, Shapechange, Storm of vengeance, True Polymorph, True resurrection, Weird, Wish 

Rigid Scales. Apophis's scales have tiny hooks all over them making it incredibly hard to hit him without getting your sword caught or getting hooked by a scale, anytime a scale hits someone they must make a dex saving throw, DC 23, or someone hits Apophis they must make a str saving throw, DC 21, or they will be hooked by a scale dealing (5d10+3) piercing damage and anything hooked will not be able to move when hooked.

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

Reactive supernova. Apophis makes a reactive supernova attack

Mountain crusher. Apophis makes a mountain breaker attack

World ender. Apophis makes a world eater attack

Extra spell. Apophis may use one of his spells