Improved Heighten Spell

(Epic Level Handbook, page 58, DnD 3.0)

[Epic, Metamagic]

You can cast a spell at any level above its own.

Prerequisite

Heighten Spell, 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.