William, Clumsy Learner

Whenever a Fractal enters the battlefield under your control, put a -1/-1 counter on William, then proliferate. {Gu}: Create a 0/0 green and blue Fractal creature token. {Gu}{Gu}: Put a +1/+1 counter on William. {Gu}{Gu}{Gu}{Gu}: Put a +1/+1 counter on each Fractal you control.