Simple yet effective, whenever a nontoken creature under your control dies, it's returned to your hand during your end step, while if an opponent's creature dies, it's immediately exiled
Tibalt (90) Duel Decks: Speed vs
This can be very strong on its own because it means that opposing players will have to discard some of their cards if Kefka is left unattended, and the user can discard valuable combo pieces in order to later retrieve them with the Commander staple called Underworld Breach, particularly if comboed with Lion's Eye Diamond to create infinite mana and then win the game
Its overpriced and made redundant by this decks other fixing, so throw in Arcane Signet instead
There are also some great dinosaur cards that work well in just about any deck they can fit into
In this case, Lotus Field Combo