Gremlight, the Rat King

Rats you control have menace, toxic 1 and "This creature cant block".
Whenever a rat enters the battlefield, you may lose 1 life and draw a card, if you do create a 1/1 black rat creature token.
At the beginning of your endstep, you may pay {p/b} , if you do return a rat creature from anywhere to its owner's hand.