Fleet Swallower, and Keening Stone

Prerequisites

• Fleet Swallower on the battlefield
• Keening Stone on the battlefield
• undefined available

Steps

1. Declare Lord Xander as an attacker, triggering its second ability, causing a player to mill half their library, rounded up
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 self-mill
• Infinite mill for target opponent