Lord Xander, the Collector, and Keening Stone

Prerequisites

• Lord Xander, the Collector on the battlefield
• Keening Stone on the battlefield
• undefined available

Steps

1. Declare Lord Xander as an attacker, triggering its second ability, causing the defending player to mill half their library, rounded down
2. Activate Keening Stone by paying and tapping it, causing the player to mill cards equal to the number of cards in their graveyard, thus milling the rest of their library

Results

• Infinite mill for target opponent