Crypt Rats

All Rats have fear. T, Sacrifice a Rat: Create X 1/1 black Rat creature tokens, where X is the number of Rats you control.

Swarm of Rats's power is equal to the number of Rats you control.

Black creatures get +2/+0 until end of turn.

Ninjutsu B (B, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Whenever this creature deals combat damage to a player, exile up to two target cards from that player's graveyard.

When this creature enters, target opponent puts a card from their hand on top of their library.

Target creature gets -2/-2 until end of turn. Flashback—1B, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

B, Discard a card: Regenerate this creature. Threshold — As long as there are seven or more cards in your graveyard, this creature gets +2/+2 and can't block.

(T: Add B.)