Pledge of Great Masteries

Whenever you cast or copy an instant or sorcery
spell, put a skill counter on Pledge of Great
Masteries. Then, you may put X +1/+1 counters
on creatures you control where X is the number
of skill counters on Pledge of Great Masteries
divided by 2, rounded up.
"To master, you must practice. To practice, you pledge
that your goals be accomplished. And sometimes, those
pledges are answered by skill and lead."
— Onari, Spellmaster