What it does
Mill means putting cards from the top of a library directly into the graveyard. "Mill 3" means the top 3 cards of that player's library go to their graveyard. It's a quantitative action—just moving cards, not "drawing" them—so effects that trigger on drawing or casting don't fire.
The biggest misconception: milling isn't a fast win condition in Commander. With four players and 99-card decks, you need to grind through far more cards than in 60-card formats, so dedicated mill is slow unless you have repeatable engines or target one opponent. Also, decking out only loses the game when a player tries to draw from an empty library, not the moment they're milled out.
Strategically, mill often works better as a tool than a kill: fueling your own graveyard for reanimation, delve, flashback, or "cards in graveyard" payoffs. Watch for opponents who want cards milled.













