Improved Heighten Spell
From Compendium of Worldly Lore
Needs review
Source: Epic Level Handbook
Description: You can cast a spell at any level above its own.
Prerequisites: Epic Level, Heighten Spell, Spellcraft (20 ranks)
As Heighten Spell, but there is no limit to the level to which you can heighten the spell.
Normal
Without this feat, a spell can only be heightened to a maximum of 9th level.