Brown/White Quest, Myr faction, for Game Day.
Combination of White Weenie Quest and Brown (Artifact) Aggro. Still working on Sideboard and a few details of which cards I can get or should include. I still need just a couple of the listed cards, for instance.
Combo #1, WW Quest:
1. Plains, Quest for the Holy Relic (0 counters), Memnite (1 counter).
2. Plains, Glint Hawk (2nd counter, Memnite back in hand), replay Memnite (3 counters).
3. Kor Skyfisher (4th counter, Memnite back in hand), replay Memnite, sac Quest for Argentum Armor on Glint Hawk. Attack w/ Hawk for 8/8 flying, destroy something good, or just land.
Short version: if Quest is in starting hand (40% chance), Argentum Armor will almost always be attacking on turn 3 or turn 4.
Combo #2, Brown Aggro:
1. Plains. Memnite, Ornithopter, Signal Pest.
2. Plains. Steel Overseer, Memnite. Attack for 3.
3. Plains. Tempered Steel, tap Overseer for +1's. Attack for 17.
Better hands could be had, but basically enough cheap artifacts + TS = fast death.
Armchair Analysis of various matchups:
Anything w/ Pyroclasm: TS means artifacts have 3/3 and don't die. If you know they've got Pyro in their deck you have 2 good choices: if you have Quest, play stuff anyway, because the counters are that important; if you have TS, consider holding guys until TS comes out. Obviously, Firewalkers = good.
Control: lots of cheap threats = lots of required cancels. Toss out a Silence on your turn the turn you plan on putting Argentum Armor on something, and that's one MORE cancel they must have. They probably don't have enough. Still, this can be a tough matchup -- you're only somewhat likely to win.
Other aggro: Your stuff costs 0 to 2. Theirs costs 1 to 2. You do the math.
Valakut: Uhmm.... Argentum attacking = no Valakut anymore. Plus Valakut takes more turns than you. Nom, nom. OK, so maybe fighting Val is never easy, but this is at least pretty likely.
Boros (RW Landfall): Probably the toughest matchup. Their weenies overpower yours on their turn and they outdamage you. AA can only take out 1 thing per turn. Consider Leonin Arbiter.
Day of Judgement: It costs 4. You kill or destroy land on turn 3. Done. Throw in Silence for more fun. If you have Quest, and it's at 5 counters but you can't kill this turn, and they'll have 4 mana on theirs, consider NOT sac'ing Quest yet.
Ratchet Bomb: About 1/3 of your creatures cost 0, about 1/2 1, and the rest 2. Ratchet won't take them all.
Speed test. As an aggro deck, speed is important. I've done several test draws against a non-playing 20HP opponent, and playing 1st (no 1st turn draw). Records:
In 31 attempts,
5 Mulligans
10 wins on turn 4
14 wins on turn 5
2 wins on turn 6
Again, clearly the opponent would be doing something during these turns and would likely slow you down.