You can recover a spell you just cast by slaying an opponent with a weapon.
Prerequisite(s): Eldritch Slayer, 5th-level eldritch knight
Benefit: If one of your attacks with a melee or ranged weapon (not with a spell) causes your target to drop below 0 hit points, you may immediately recover one spell or spell slot that you used this round or in the previous round (but not earlier). You may use this ability once per day per 3 levels of eldritch knight you possess.
Undefeatable: The Collected Feats Sourcebook, Copyright 2009 – 2010, Louis Porter Jr. Design, Inc. Undefeated, Copyright 2011, Louis Porter Jr. Design, Inc.