Lord Xander, the Collector + Keening Stone

Lord Xander, the Collector

Keening Stone

How it works

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 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.