Activate Zedruu by paying {U}{R}{W}, giving control of Moderation to an opponent.
Whenever the opponent that controls Moderation casts a spell from their hand, Knowledge Pool triggers, exiling that spell.
Because Moderation 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.

Exile all spells target opponent casts from their hand

Target opponent can only cast one spell per turn

Lock

Knowledge Pool

Moderation

Zedruu the Greathearted

Cast Fractured Identity by paying {3}{W}{U}, exiling Moderation and causing each opponent to create a token copy of it.
Cast Knowledge Pool by paying {6}.
Whenever an opponent casts a spell from their hand, Knowledge Pool triggers, exiling that spell.
Because Moderation 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.

Exile all spells opponents cast from their hands

Opponents can only cast one spell per turn

Fractured Identity

Cast Fractured Identity by paying {3}{W}{U}, exiling Moderation and causing each opponent to create a token copy of it.
Any time an opponent would cast a spell, Possibility Storm exiles that spell and reveals cards until you find one they could cast.
The opponent's Moderation prevents them from casting a second spell resulting in a lock.

Combos with "Moderation"