The "Into the Breach" deck is all about two things: speed and synergy. On their own, cards like Ornithopter (a 0/2 flier) and Memnite (a 1/1 creature with no abilities) are not exactly going to end games quickly. Combined with powerful battle cry cards like Signal Pest and Goblin Wardriver, however, those unassuming zero-mana creatures can really pack a punch!
Your game plan is basically going to proceed in two stages. First, deploy as many threats to the battlefi eld as you can. These can take the form of token creatures from Kuldotha Rebirth and Devastating Summons (it's okay to cast the Summons for two 1/1s—they'll get bigger fast!) or the aforementioned Memnites and Ornithopters. What matters isn't how good your creatures are individually; you just want to get them on the board as soon as possible. Goblin Guides are fine to cast on turn one, but since they have haste it's usually better to get your other threats out first. After your army has populated the battlefi eld, cast Goblin Bushwhacker and creatures with battle cry to pump up your waves of attacking creatures, ideally dealing 10 or 12 damage at a time. Meanwhile, spells like Lightning Bolt, Galvanic Blast, and Panic Spellbomb will make sure that pesky blockers won't get in your way.
If things go according to plan, you'll capture the first game very quickly. Then, it's time to use your sideboard. The key is not to bring in a card unless you're pretty sure you need it. Getting pounded by a few expensive threats? Use Goblin Ruinblaster to ensure your opponent has trouble finding enough mana to cast them. Are your opponents playing a lot of artifacts? Th at's a perfect time to call Into the Core up off the bench and make them pay.
There are several diff erent directions you could take the deck if you decide to change things up a little bit. One route involves making it even faster, maxing out on Goblin Guides, Goblin Bushwhackers, Contested War Zones, and the powerful Mox Opal to win the game before your opponent knows what's happening. Alternatively, you can trade short-game power for long-game resilience and stability by including higher-cost spells like Hero of Oxid Ridge and Koth of the Hammer, allowing your deck to pack that extra punch in the later turns.
Into the Breach
Mirrodin Besieged Event Deck
To win with the "Infect & Defile" deck, you'll need to be patient. Your deck is not designed to be aggressive, and if you simply cast your creatures and attack with them, you may find yourself quickly outmatched. Your deck has two primary advantages: first, a potent long-term plan—that is, given enough time, you'll draw more cards, have more creatures, and cast more spells. Second, you can eff ectively ignore your opponent's life total. Your deck is packed with creatures with infect. Every damage dealt to opponents from these creatures takes the form of poison counters, and a player with ten poison counters loses the game.
Early on, use cards like Smother, Mana Leak, and Necropede to stall the board and trade with your opponent's creatures, getting in a point of damage here and there. It's okay to let some of your early creatures die; you can get them back later with Corpse Cur. Then, use spells like Foresee and Consuming Vapors to pull ahead after the initial assault has been blunted.
One important thing to remember is that, if your opponent lets his or her guard down, you can win with shocking speed. Say you've just cast a Phyrexian Vatmother, and your opponent taps out next turn for a Baneslayer Angel. Even if you haven't attacked once this game, a single Corrupted Conscience on the Angel will have your opponent facing down a lethal attack the very next turn. So look for opportunities to put your opponent on the defensive when he or she least expects it.
Your main deck is designed to compete against an open field, but your sideboard gives you backup against a variety of opposing strategies. Bring in cards like Go for the Throat and Doom Blade against faster creature-based strategies. On the other hand, if your opponent is also playing for the long game, Negate will ensure that their most powerful spells never see the light of day.
You may choose to evolve the deck, taking it in one of several possible directions. One route would be to focus on adding more creatures with infect like Phyrexian Vatmother and Phyrexian Crusader to assume a more proactive approach. Alternatively, you could focus on controlling the long game with countermagic like Mana Leak and removal like Black Sun's Zenith, polishing the opponent off with huge finishers like Consecrated Sphinx.
Infect & Defile
Mirrodin Besieged Event Deck