Master of Rats

Rat Creatures you control get +1/+1.
At the beginning of each opponents Attack step, once they declare Attackers, you may pay {5}. If you do, Put X 2/2 Black Rat creature tokens with Deathtouch onto the battlefield, where X is the number of attackers that opponent declared. Exile the tokens at the end of Combat.
"People often underestimate Rats. I will correct their foolish mistake."