Improved Heighten Spell
( Epic Level Handbook, p. 58)[Epic, Metamagic]
You can cast a spell at any level above its own.
Prerequisite
Heighten Spell (PH) , Spellcraft 20 ranks,
Benefit
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.