Impromptu Dispelling (3.5e Feat)
From D&D Wiki
Impromptu Dispelling [Psychic]
Prerequisite: , Psychomagic
Benefit: On a successful Knowledge (arcana) check (DC 15), you can cast dispel magic without advance preparation (even if you don't know the spell), by sacrificing one or more spells with a total level of at least 3. Failing the check means that you don't succeed that round, but you don't lose the spells and you can try again next round without penalty. If successful, your total character level is used to determine the power of the Dispel Magic (including racial hit dice and level adjustment).
Note: Related to Psionic Gifts Variant Rule