Lavinia, Azorius Renegade + Knowledge Pool

Lavinia, Azorius Renegade
Knowledge Pool

Requires
All permanents on the battlefield.
Steps
  1. Whenever a player casts a spell from their hand, Knowledge Pool triggers, exiling that spell and allowing them to cast a spell exiled by it without paying its mana cost
  2. When an opponent casts a spell this way, Lavinia triggers, countering that spell
Results
Exile all spells players cast from their hands. Counter all spells opponents cast that are created by Knowledge Pool.