Requires

Knowledge Pool must be on the battlefield. Colfenor's Plans must be on the battlefield. Harmless Offering must be in hand. Mana needed:

Steps

1. Cast Harmless Offering by paying , giving control of Colfenor's Plans to an opponent.
2. Whenever the opponent that controls Colfenor's Plans casts a spell from their hand, Knowledge Pool triggers, exiling that spell.
3. Because Colfenor's Plans prevents the opponent from casting more than one spell each turn, the opponent cannot cast the spell permitted by Knowledge Pool, or any other spell that turn.

Results