Master Staff
( Epic Level Handbook, p. 62)[Epic]
You can activate a staff without using a charge.
Prerequisite
Craft Staff (PH) , Spellcraft 15 ranks,
Benefit
When you activate a staff, you can substitute a spell slot instead of using a charge. The spell slot must be one you have not used for the day, though you may lose a prepared spell to emulate a wand charge (you may not lose prepared spells from your school of specialty, if any). The spell slot lost must be equal to or higher in level than the specific spell stored in the staff, including any levelincreasing metamagic enhancements. You cannot emulate a charge for a staff function that does not match a specific spell. For example, you might want to save the charges on your staff of power because you do not want to go to the trouble of crafting another when the charges run out, and also because it allows you more options--you can memorize more utilitarian spells, trusting to the offensive power of your staff if conflict arises. You can use this feat to lose a 3rd-level prepared slot in order to active lightning bolt from the staff, but you can't use this feat to emulate a charge used for doubling the staff's melee damage (because that power doesn't match a specific spell).