Fraying Sanity, and Lord Xander, the Collector

Prerequisites

• Fraying Sanity on the battlefield
• Lord Xander, the Collector on the battlefield

Steps

1. Declare Lord Xander as an attacker
2. Its second ability triggers, causing the defending player to mill half their library, rounded down
3. At the beginning of your end step, Fraying Sanity triggers, causing the opponent to mill cards equal to the number of cards put into their graveyard this turn

Results

• Infinite mill for target opponent