Warum nicht, dass alle Xp-Kosten halbiert werden, das wäre einfacher?
Allerdings finde ich nciht, dass die Fähigkeit passt.
Was wäre mit:
Divine Assistance (Ex):
As a swift action, an epic cleric of 40th level or higher can ask his patron for assistance. There is a chance of 1% per class level that his patron is responsive to his prayer. In that case, the patron will help the cleric up to a number of one round per class level.