Opposition Agent, Hive Mind, and Doomsday

Prerequisites

• Opposition Agent on the battlefield
• Hive Mind on the battlefield
• Doomsday in hand
• Your life total is at least 2
• available

Steps

1. Cast Doomsday by paying
2. Hive Mind triggers, causing each opponent to copy Doomsday
3. Resolve the first opponent's Doomsday, searching their library and/or graveyard for any five cards, exiling them due to Opposition Agent, exiling the rest of their library and graveyard, and causing them to lose half their life, rounded up
4. Repeat step 3 for each other opponent

Results

• Exile each opponent's library
• Near-infinite lifeloss