Gravemind, Undying Plague

: Whenever a non-Flood creature is killed by a Flood creature, return it to the battlefield under your control. It becomes a Flood creature.
X: Sacrifice a creature with base toughness X. Gravemind gains its activated abilities. Create X 1/1 flood spore creature tokens.
-X: Destroy target creature with base toughness X. Gravemind gains its activated abilities. Create X 1/1 flood spore creature tokens.