Activate Zedruu by paying ({U} magic symbol) ({R} magic symbol) ({W} magic symbol) , giving an opponent control of Lich's Mastery.
If needed, activate Shadowspear by paying ({1} magic symbol) , causing all permanents your opponents control to lose hexproof and indestructible until end of turn.
Cause Lich's Mastery to leave the battlefield.
Lich's Mastery triggers, causing its controller to lose the game.