PLEASE NOTE: The Swamps in the decklist actually stand in for 2/2 Zombie tokens (which you can't use in the TappedOut deckbuilder). The Snow-covered swamps similarly are meant to be 5/5 Zombie Giant tokens.
A mono-black zombie deck for a format called 'The Horde', which is a co-op variant for EDH. Basically you have one Horde deck and up to 4 players. Shuffle the deck then take out 25 cards if there are only 3 players, 50 cards if there are only 2 players, or 75 cards if there is only one player. The Survivors team is considered one player a la 2-Headed Giant. Some players (my playgroup atleast) like to add a real fun set of rules here. Basically, any effect which says 'your hand', 'your deck' 'you control', etc, you can choose to use another Survivor's hand, deck, creature, etc. Makes all the decks synergise in fantastic ways.
For the first 3 rounds, the Horde will not get a turn at all. It doesn't start with any cards in its hand, either. After the Survivors' 3rd turn, the Horde will join the game. Each turn, The Horde untaps, then reveals cards from the top if its deck until it reveals a non-token card. First, all of the tokens go onto the battlefield. Then the non-token card is cast. All creatures controlled by the Horde have Haste and must attack each turn if able. For any sort of additional costs or flashback or player effects or what have you, we like to play it as if the Horde always has infinite black mana at all times. So if for whatever the reason the Horde would benefit from paying mana towards an effect you control, it will always do so to its fullest extent. As well, if it ends up with cards in its hand or the option to pay to do something, it would always do as much as it can each turn. Assume that the Horde will always follow common sense and do what's best for itself.
The Horde has no life total. When you would cause it to lose life or gain Poison counters, instead mill that many cards off the top of the Horde deck. If an effect would cause the Horde to gain life, instead shuffle the Horde's graveyard and then put that many cards from the graveyard back on top of the Horde deck. The Horde will lose the game only if it starts its turn with no cards in its library. Oh, also, the Zombie tokens in the deck are treated like actual Creature cards with mana cost 0, not tokens. Tokens created by effects are to be
treated like normal tokens.
The 4 decks you play against the Horde are totally up to you. I encourage you to alter the Horde deck too. Add cards you think your playgroup would enjoy. We're also thinking about maybe making mono-coloured decks of the other 4 colours to play as 'Survivor Decks', where you choose a class to fight the Horde with by selecting one of these pre-constructed decks.
Most of the deck and the entirety of the concept from here http://www.quietspeculation.com/2011/09/horde-magic-a-new-way-to-play-magic-and-survive-zombie-invasions/
