When Karumonix enters, look at the top five cards of your library. You may reveal any number of Rat cards from among them and put the revealed cards into your hand. Put the rest on the bottom of your library in a random order.
Flood the board with Rats, grant them all toxic, and kill the table via poison counters (10 = dead) backed by go-wide combat damage. Karumonix refills your hand with Rats every time it enters, so you rebuild quickly through removal and grind out wide, evasive attacks.
Anthem that turns a wide Rat board into lethal toxic damage fast.
Add proliferate enablers (Tekuthal, Vraska, Thrummingbird) to accelerate poison kills, and tighten the curve with token doublers and anthems. Improve ramp with Cabal Coffers, Urborg, and Crypt Ghast, and add protection like Heroic Intervention plus board-wipe insurance such as Skullclamp and recursion to recover after wraths.