This deck is simple, but it actually does great against every deck that relies on creature damage. Including speed rainbows.
(Note about speed rainbows: try not to play the discord until late game, since scrambling their quanta won't matter much and you REALLY don't want it stolen).
Hover over cards for details, click for permalink
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Basically, spam stuff. Antimatter high attack creatures (wait as long as possible for those with growth, etc etc). I like to calculate the damage swing when deciding whether or not to antimatter something (6 attack has a 12 swing, a 10 attack shrieker has a 15 swing due to burrow, a 13 attack lava golem has a 24 attack swing due to growth...)
Now for the card breakdown and why they're necessary...
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Amethyst Dragons: Your main damage dealer, since you need a win condition. They have 6 health so can usually survive long enough to either do enough damage for discord to finish or win. They also survive longer when you have a discord out to scramble quanta the opponent could use for control.
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Antimatter: The reason this deck is so dang good. Basically how you survive until you win. I've even decked out a speed rainbow before thanks to them.
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Discord: Another important card to the deck, with 3 copies in case 1-2 gets destroyed and also to make them much easier to draw early. First turn discord is pretty disheartening, and can enable you to simply out rush almost any mono-duo deck. Even speed poison/mono aether can be beaten with it out early despite the antimatters being almost non-factors against it.
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Purple Nymph: Not required, and in some cases I would actually rather have an antimatter CARD, since those can't be controlled. Against speed rainbows it will usually die pretty fast, and I use it so I have a 7th card that can produce antimatter. If you don't have one, it can be replaced by a unupped shield, another tower, a chaos seed, etc.