Liam, Aslumb

Liam, Aslumb enters the battlefield with a
slumber counter on it.
Creatures you control get +1/+1 for each
slumber counter on Liam, Aslumb. Liam,
Aslumb can't attack as long as it has a slumber
counter on it.
{t}, {2}{g/u} or {4}: Proliferate or remove a
slumber counter from Liam, Aslumb.