Cast Mordenkainen by paying {4}{U}{U}.
Mordenkainen enters the battlefield with ten loyalty counters due to Doubling Season.
Activate Mordenkainen's third loyalty ability by removing ten loyalty counters from it.
Mordenkainen dies as a state-based action due to having zero loyalty.
Resolve the Mordenkainen ability, exchanging your hand and library.
Cast Thassa's Oracle by paying {U}{U}.
Thassa's Oracle enters the battlefield, causing you to win the game.

Infinite card draw

Win the game

Mordenkainen

Doubling Season

Thassa's Oracle

Cast Mordenkainen by paying {4}{U}{U}.
Mordenkainen enters the battlefield with ten loyalty counters due to Vorinclex.
Activate Mordenkainen's third loyalty ability by removing ten loyalty counters from it.
Mordenkainen dies as a state-based action due to having zero loyalty.
Resolve the Mordenkainen ability, exchanging your hand and library.
Cast Thassa's Oracle by paying {U}{U}.
Thassa's Oracle enters the battlefield, causing you to win the game.

Combos with "Mordenkainen"