Callin, Dean of Lessons

{t}: Add {w}, {u}, {b}, {r}, or {g}. The next instant or sorcery spell you cast has Demonstrate. Once it resolves, exile it.

At the beginning of each end step, each player who created a copy of a spell through demonstrate Learns.
(You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)