Phenax, God of Deception | Sewer Nemesis | Lord Xander, the Collector

Cards

All permanents on the battlefield (
Sewer Nemesis without summoning sickness and with an opponent chosen and
Lord Xander without summoning sickness).

Declare
Lord Xander as an attacker attacking the opponent named by
Sewer Nemesis.
Lord Xander's second ability triggers, causing the opponent to mill half their library, rounded up.
Activate
Sewer Nemesis by tapping it, causing the opponent to mill cards equal to the cards in their graveyard, milling the remainder of their library.