Heighten Spell, Improved (Feat)

You can use your arcane skill to make your magics nearly impossible to resist

Prerequisites: Caster Level 21, Heighten Spell (Feat)

Benefit: As Heighten Spell (Feat), but you can heighten the spell above 9th level spell slots.

Level Increase: Varies (An Improved Heightened spell is as difficult to prepare and cast as a spell of its effective level. While Improved Heighten Spell does not natively require a higher spell slot to use, it allows a higher level spell slot to be used, and when this is done, the spell's DC and all other effects are calculated as if it was of that higher level.)