Dauthi Voidwalker, and Helm of Obedience

Prerequisites

• Dauthi Voidwalker on the battlefield
• Helm of Obedience on the battlefield
• available

Steps

1. Activate Helm of Obedience by paying and tapping it, causing an opponent to mill the card
2. The card is exiled instead of being put into the opponent's graveyard due to Dauthi Voidwalker, which causes the process from Helm of Obedience to continue until the opponent has exiled their entire library

Results

• Exile target opponent's library