Editing Golgari Swarm (section)

==Mechanics==
=== Dredge ===
[[Dredge]] is one of the most powerful key word mechanics in M:tG. A small entry here is not able to do justice to the influence it had, and continues to have, on the metagame and ban lists of multiple formats.

Simply put, a card with Dredge allows you to return it to your hand from the graveyard as an alternative to drawing a new card card whenever you are able to draw a card. In exchange you take X cards from the top of your library and put them in the graveyard. This is broken because in a deck built around abusing Dredge you have lots of cards that can be pulled from the graveyard to your hand, so in effect Dredge is "Put this card in your hand and then make so many cards available for you to then put into your hand later", this breaks the game because it basically ignores a bunch of rules that other decks have to follow. It also has a few other bullshit strengths such as being immune to most disruption effects (opponent makes you discard a card, bring it back and then add a bunch of cards into that pool of potential dredge cards in your graveyard). Not to mention that when built right the graveyard is basically an extension of the player's hand which leads to circumventing the hand limit without having to bother with an artifact, enchantment or creature that can get removed and force you to dump the hand. Coupled with Black's frequent return from the graveyard creatures and cards, triggers based on cards going into or out of the graveyard, sacrifice triggers etc, it can be very, very frustrating playing a Dredge deck that flatout plays an entirely different game of Magic. 

Countering Dredge isn't hard so much as having super-specific cards on hand that can stop it. But these cards do fuck all against everything else except a few related archetypes like Reanimator and decks that rely on recursion meaning that you will almost never have the right cards main-decked for game 1 unless Dredge (or other graveyard) decks are on the upswing in popularity in the meta. Game 2 is about how well the Dredge player can recover from being castrated by cards like Leyline of the Void, or (more likely) their ability to sufficiently gain the upper hand before castration and be able to win the game (or better yet, for them, beat you before you castrate them).

=== Scavenge ===
Scavenging a creature in the graveyard means exiling it and putting +1/+1 equal to its power on one of your field creatures, for a cost (which is independent of the casting cost, unless it's scavenge is being granted by [http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=368977 Varolz, the Scar-Striped]). Coupled with a quick and huge ramp (a given with green), a large amount of scavengable creatures, sacking and triggers-on-sacking (a given with black) this can result in a huge stampede of creatures with ridiculous power/toughness. Keyword-givers round out the field populator. 

Scavenge may seem as [[cheesy]] as dredge, but defenses exist in the form of counters (preventing keywords being given) deathtouch creatures (ubiquitous) and penalizing and boardwipe spells, effectively rendering the enemy's wall of meat and muscle a moot point.

===Undergrowth===
Undergrowth is less so much an ability, and more a signpost that says, "The following effect cares about how many creatures are in your graveyard". Usually this means something like giving a creature +X/+X where X is the number of creatures in your graveyard.