What it does
Sweep is a mechanic from Saviors of Kamigawa that lets you return any number of lands of a specific type (like Plains or Forest) from the battlefield to your hand, with the spell or ability getting stronger based on how many you returned. For example, Sink into Takenuma reads "Sweep—Return any number of Swamps... Target player discards a card for each Swamp returned this way."
The key nuance: you choose how many lands to return, and you can choose zero. Returning lands is a cost, so it can't be responded to or prevented once you're paying it. The lands go back to your hand, not your library, so you're trading board presence for a bigger effect right now.
In Commander, Sweep is mostly a fringe pick. Sacrificing land development for a one-time bonus is usually too slow in multiplayer, though it can shine if you're already flooded or running land-recursion synergies.



