Apotheosis

By affirming and speaking ones true name, the spark of divinity reignites within you, granting you a measure of your former godly powers.

Aside from your physical appearance reverting to its true form, you gain the following benefits:
+100 hit points
Resistance to any magic that would change your physical form
Resistance to any magic that would otherwise effect your mind
+5 to you initiative rolls
+5 to your AC
You gain a fly, swim and burrow speed of 60feet
You gain 2 legendary actions that can be used to cast a cantrip of your choice (legendary actions are replenished at the top of the initiative order)
You gain 2 legendary resistances which replenish upon a long rest

In addition to these benefits, whenever you cast a spell, roll a d20. If the result is less than half your charisma stat (Rounded down) then the applicable spell slot is not consumed. 

IMPORTANT NOTE: In accordance with the binding truce between Gods and Primordials, neither party can exist on the Material Plane. When casting this spell roll 5d6 and record the result. After a number of days have elapsed equal to this number your characters physical form is irrevocably destroyed. Your divine essence then travels to the outer plane that corresponds to your alignment as you take your place as a demi-god. There is no magic or ability that can prevent, undo or reverse this effect. If the character should perish this effect will persist as the divine essence cannot be destroyed.