Toothy, Imaginary Friend

Legendary Creature — Illusion

Partner with Pir, Imaginative Rascal (When this creature enters, 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. When Toothy leaves the battlefield, draw a card for each +1/+1 counter on it.

Go ahead, tell it that it isn't real.