Dredge
Dredge is the keyword attributed to the Golgari in the Ravnica block. It is a mechanic of recursive nature, where the owner of a card in a graveyard with said ability can return the card to their hand by choosing to skip his or her draw and put a number of cards from his or her library into his or her graveyard. The actual number of cards that must be put into a graveyard is written on each card with Dredge. Dredge only appears on green and/or black cards as well as on the Dakmor Salvage on the Future Sight keyword land cycle
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Ichorid
One of the most popular uses of Dredge is to use it to quickly fill your graveyard. A famous deck based on Ichorid originated from this concept. Such decks work best with cards with high Dredge values, such as Golgari Grave-Troll and Stinkweed Imp. The Extended Dredge deck was a common deck archetype built around this mechanic.
Life from the Loam
The dredge card Life from the Loam has since it's release found widespread tournament use fueling a wide array of decks. Life from the Loam works as an engine producing additional targets for itself when dredging. In combination with Onslaught cycling lands it is regrowable at instant speed and Onslaught Fetch Lands it gives color stability. It was also widely used to regrow other utility lands like Wasteland and Cephalid Coliseum. The card has been widely used to fuel cards requiring discard and specifically discard of lands such as Solitary Confinement, Seismic Assault and Raven's Crime.