Edwin, the Snapcaster

Defile 4 — Whenever exactly four cards are put into your graveyard from anywhere, if Edwin, the Snapcaster isn't defiled, it becomes defiled and tap it. It can't untap for as long as it's defiled.
Whenever a creature you control attacks, if Edwin is defiled, you may sacrifice that creature. If you do, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to i