Wickerbottom, Librarian

Wickerbottom, Librarian enters the battlefield
with 5 sanity counters on it.
Whenever you cast a sorcery, remove sanity
counters from Wickerbottom equal to its cost.
If you do, you may cast a copy of that spell
for free at the beginning of your next upkeep.
{t}, {x}{u}: Place X sanity counters
on Wickerbottom, Librarian.