Toothy, Imaginary Friend

Toothy, Imaginary Friend {3}{U}

Legendary Creature - Illusion | Power/Toughness: 1 / 1 (CMC 4)
Partner with Pir, Imaginative Rascal (When this creature enters the battlefield, target player may put Pir into their hand from their library, then shuffle.)
Whenever you draw a card, put a +1/+1 counter on Toothy, Imaginary Friend.
When Toothy leaves the battlefield, draw a card for each +1/+1 counter on it.