Doomsday Excruciator, and One Ring to Rule Them All

Prerequisites

• Doomsday Excruciator in hand
• One Ring to Rule Them All in hand
• plus eight available

Steps

1. Cast Doomsday Excruciator by paying
2. When Doomsday Excruciator enters, it triggers, causing each player to exile all but the bottom six cards of their library
3. Cast One Ring to Rule Them All by paying
4. When One Ring to Rule Them All enters, its first chapter ability triggers, causing Doomsday Excruciator to become your Ring-bearer and causing each opponent to mill the rest of their library

Results

• Infinite mill
• Near-infinite self-mill