Teferi, Time Raveler + Knowledge Pool
How it works
- Because of Teferi, opponent can only cast spells whenever they could cast a sorcery.
- Whenever they cast a spell from their hand, Knowledge Pool triggers, exiling that spell.
- The opponent cannot cast the spell as permitted by Knowledge Pool due to Teferi.
This potent lock relies on Teferi, Time Raveler's static ability restricting your opponents to casting spells only any time they could cast a sorcery, fundamentally breaking how Knowledge Pool operates. When an opponent tries to cast a spell from their hand, Knowledge Pool's triggered ability forces them to exile that spell and attempts to let them cast another exiled card without paying its mana cost. However, because Knowledge Pool's replacement effect happens during the resolution of a spell cast (when the stack is not empty), Teferi's timing restriction prevents your opponents from legally casting anything from exile. The net result is a devastating hard lock that exiles every spell your opponents try to cast from their hands while leaving them completely unable to cast anything in return.