Liam, Budding Intellectual

Liam is hexproof, except when in slumber
Slumber 2 (You may tap Liam at your upkeep. If you
do so, at your end step double Liam's power and toughness, and put a slumber counter on Liam)
{x}{u}{r}{t}: Deal X damage to any target, where X is
the number of slumber counters on Liam. Return
Liam to owner's hand with zero counters.
Study while others are sleeping, and dream while others
are wishing