Defender (This creature can't attack.)
: Flowstone Wall gets +1/-1 until end of turn.
Whenever you discard a card, you may sacrifice Pitchstone Wall. If you do, return the discarded card from your graveyard to your hand.
At the beginning of your upkeep, Wall of Tombstones's toughness becomes 1 plus the number of creature cards in your graveyard. (This effect lasts indefinitely.)