Fleet Swallower + Keening Stone

Fleet Swallower

Keening Stone

How it works

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 5 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.