Horde rules

• Horde: Survivors bring decks of at least 40 cards, with up to four copies of each card other than basic lands. A good home for draft and sealed decks.
• Commander Horde: Survivors bring normal Commander decks. The command zone and commander tax work as usual. Commander damage never comes up, since the Horde has no commander and no life total.
• Both formats use the Survivor ban list below.

• The Survivors win when the Horde has no cards in its library, no cards in its hand, and no creatures on the battlefield.
• The Horde wins when the Survivors' group life total is 0 or less at the end of a Horde turn. Everyone shares one life total, so the team wins or falls together.
• SlingLab checks both automatically and ends the game for you.

• Like Two-Headed Giant, the Survivors are one team: they take their turn at the same time, and attack and block together.
• The Survivors get 3 turns to set up before the Horde's first turn (the host can change this). Then turns alternate: Survivors, Horde, Survivors, and so on.
• The group life total is 20 per Survivor by default: 1 Survivor: 20, 2 Survivors: 40, 3 Survivors: 60, 4 Survivors: 80. The host can pick a different amount per Survivor, "100 minus 15 per extra Survivor" (100/85/70/55), or one fixed total.

The Horde has no player. When its turn starts, SlingLab plays it for you:

• Every Horde permanent untaps.
• Cards are revealed off the top of the Horde's library until a card that isn't a token comes up (against a bigger team, until several do: see Difficulty). Every revealed token enters the battlefield, and every nontoken card is cast.
• The Horde casts every card in its hand. Its flashback cards (and the like) are cast from its graveyard by difficulty: never on Story, on a coin flip's Yes on Classic (the log shows the coin), and always on Nightmare, but never on the same turn the card was cast. Cards with their own condition, like Gravecrawler, go on offer in the Horde panel at every difficulty, since only the table can check the condition. Casting them is optional, so a Yes/No coin beside each says whether the Horde does.
• The Horde has unlimited mana, so it can always pay any cost. Instants and sorceries wait on the Horde panel until a Survivor resolves their effect by hand and presses Done.
• Abilities the Horde would have to activate are never activated. Triggered and static abilities work as normal.

• Every Horde creature has haste and attacks every turn if able. When the Horde's turn runs, every untapped Horde creature taps and attacks the Survivors.
• The Survivors block as a team, deal and take damage, and resolve triggers by hand. Then any Survivor presses End the Horde's turn.
• SlingLab rule: the Horde never blocks. When the Survivors attack, their combat damage goes straight to the Horde.

• The Horde has no life total. Damage dealt to it, or life it would lose, mills that many cards off its library instead. Use Hit the Horde on the Horde panel.
• Lifelink still works for the Survivors. Raising the Horde's life on its panel puts its newest graveyard cards back on top of its library (for a misclick). With its graveyard empty, each point is real life gain: a new copy of one of its deck's tokens goes on top of its library, and the whole table is alerted.
• The Horde's own token cards (the ones in its deck) go to its graveyard like any card, whether milled or killed, so the graveyard always accounts for the cards it has lost. Tokens made during play still cease to exist when they leave the battlefield.

• The Horde never makes a choice of its own; chance makes them instead. Optional and conditional actions are settled by a Yes/No coin flip that every Survivor sees the same way:
  • Optional and conditional actions. A Horde card on the battlefield whose text says "you may", or that has an ability it could activate (like Carrion Feeder's "Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder"), carries its own coin flag, green Yes or red No, that flips again at the start of every turn. On Yes the table takes that action for the Horde this turn; on No it doesn't. Mana abilities never get a coin, since the Horde never pays mana, and neither do things the card makes happen anyway.
  • Casting from the graveyard. Cards the Horde may cast from its graveyard under a condition (Gravecrawler) go on offer in the Horde panel, whose Graveyard button flashes until they're dealt with. Each shows its coin and lights up the button it picked: check the condition, then Cast on Yes or Skip on No.
  • Flashback. The Horde handles flashback cards itself, by difficulty (see Difficulty): on Classic it flips the coin and casts on Yes, and the game log shows the flip.
• Targets are picked for the Horde automatically when its card has only one sensible kind of target, with an arrow showing the pick. For anything else, use Roll for the Horde to pick a random Survivor or a random Survivor creature; the result goes in the game log for everyone.
• Every Survivor still in can handle the Horde's cards: move, tap, destroy or bounce them, and create tokens for the Horde (for cards like Army of the Damned). The Horde is everyone's shared puppet.

The host sets the difficulty in the lobby. Every option comes from the wiki's list of ways to tune the Horde.

Custom exposes each one: 1 to 6 set-up turns, exiling 0%, 10%, 25%, 40% of the Horde deck at random before the first turn, and whether the Survivors may attack the Horde during set-up, and whether the Horde casts its flashback cards never, on a coin flip, or always. Exiling part of the Horde is the main way to make a one or two Survivor game fair. Starting life is always its own choice.

The Horde grows with the team. A plain Horde deck is the same 100 cards with the same waves whether one Survivor plays or four, while four Survivors deal about four times the damage. So on every preset:

• Each Survivor after the first adds 50 cards to the Horde's library, copied from the deck itself: 30 of its tokens and 20 of its regular cards, so a bigger team faces a bigger swarm (100/150/200/250 cards for 1-4 Survivors).
• Each Horde turn reveals until more nontoken cards come up. For 1-4 Survivors: Story 1/1/1/2, Classic 1/1/2/2, Nightmare 1/2/3/4.
• Three or four Survivors get one less set-up turn (never fewer than one).

On Custom, the host sets the Horde's deck size (100 to 1000 cards; the extra cards keep the same 30/20 split of tokens and regular cards) and how many nontoken cards each wave reveals until (1 to 10). Either can be left on Auto, which grows with the team like Classic. Custom always plays exactly the set-up turns the host picked.

It gets worse the longer you last.

• Surge: every few Horde turns (every 4 on Story, 3 on Classic, 2 on Nightmare) the Horde surges, and from then on its waves reveal one more nontoken card, up to 4 more. It surges on those Horde turns themselves: on Classic, Horde turns 3, 6, 9 and so on. The log calls each one out, and the Horde's toolbar shows the wave number, the surges so far, and when the next one lands. Custom picks every 2, 3, 4, 5 turns or Off.
• Rally (Nightmare, or Custom when the host turns it on): at the start of each Horde turn, before its wave, every Horde creature already on the battlefield gets a +1/+1 counter. Whatever the Survivors leave standing keeps growing.

Every Horde deck is 100 cards: 60 tokens and 40 regular cards. Per the wiki, the cards avoid making the Horde choose, which rules out almost every card that targets.

Peter Knudson's list of cards that win too easily against a deck that can't make choices. Survivor decks can't contain any of them; the lobby checks before the game starts.

Aether Flash, Aurification, Barbed Foliage, Caltrops, Crawlspace, Dueling Grounds, Dread, Elesh Norn, Grand Cenobite, Ensnaring Bridge, Eradicate, Grindstone, Haunting Echoes, Island Sanctuary, Lethal Vapors, Leyline of Singularity, Magus of the Moat, Mind Funeral, Moat, No Mercy, Platinum Emperion, Platinum Angel, Silent Arbiter, Solitary Confinement, Stormtide Leviathan, Surgical Extraction, Tainted Aether, Teferi's Moat, Time Stretch, Trepanation Blade, Urabrask the Hidden