Elemental Body (all)

Each mythic elemental body spell must be learned individually, and you must know the respective non-mythic elemental body spell to learn its mythic version. You don't have to learn them in order, and aren't required to know a lower-level mythic elemental body spell before you learn a higher-level one (for example, you can learn mythic elemental body II if you know elemental body II, even if you don't know mythic elemental body I). Each mythic elemental body spell adds the following benefits to its respective non-mythic version.

The spell's bonuses to ability scores increase by 2, the natural armor bonus increases by 1, and the ability score penalties decrease by 2 (minimum penalty of 0). There is a 50% chance any critical hit or sneak attack against you is treated as a normal hit, as if you were wearing medium fortification armor.

Augmented (3rd): If you expend two uses of mythic power, the ability score bonuses increase by an additional 2. You can also, a number of times equal to your tier, add half your tier to the DC of one spell you cast with an energy descriptor that matches your elemental type (air: electricity, earth: acid, fire: fire, water: cold).