Thought Rattle (YBLB-030) - Alchemy: Bloomburrow

Target opponent reveals each nonland card in their hand. You choose one of those cards. Exile that card.
Threshold — If seven or more cards are in your graveyard, seek a Rat card. It perpetually gains "This spell costs {1} less to cast."
You gain 1 life for each Rat card in your hand.