Opposition Agent + Sudden Substitution + Selective Memory

Opposition Agent

Sudden Substitution

Selective Memory

How it works

1. Cast Selective Memory by paying 3.
2. Holding priority, cast Sudden Substitution by paying 2, exchanging control of Selective Memory and target creature an opponent controls.
3. Resolve Selective Memory, choosing to have the opponent exile all nonland cards in their library due to Opposition Agent.

This clever puzzle relies on handing your own spell to an opponent while a replacement effect is waiting to pounce. By casting Selective Memory, you set up a mass-exile spell, but before it resolves, you use Sudden Substitution's split second to swap that spell's control with a creature your opponent owns. Because Opposition Agent is already on your battlefield granting you control of your opponents while they search, your opponent is forced to search *their* library for Selective Memory's effect—meaning they end up banishing all the nonland cards from their own deck directly into exile under your control.