Karumonix, the Rat King

Toxic 1 (Players dealt combat damage by this
creature also get a poison counter.)
Other Rats you control have toxic 1.
When Karumonix enters the battlefield, 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.