Negative Iron Man, henceforth referred to as -Iron Man, is the best card in the game hands down and can turn your weakest locations into winners. The point of this deck is to find and play -Iron Man as many games as possible and to follow him up with -Mystique to all but guarantee the win. This deck is a primarily 2 lane deck that requires you to make some good decisions on which two lanes you're going to compete in.
Piloting:
Even though your objective is simple, piloting this deck can be difficult. You're usually playing for just 2 lanes so you have to be on point with your decision making on where to place each card as you're building up your positions. You've also got to be aware of exactly what's in your deck so you know the probability of drawing Iron Man and/or Mystique.
Snapping:
Don't snap before all 3 locations are revealed. Weirdworld and Subterranea screw you over completely. Mindscape screws you over if you don't have Magik. Sanctum can be very difficult depending on the other two locations since this deck likes to dump weak utility cards like Nakia into the third lane. Assuming the game locations are workable, Snap when you've got Psylocke in hand by turn 2 and Mr. Negative in hand by turn 3. Also consider snapping anytime you're able to play Mr. Negative and Iron Man isn't in hand (especially if you're able to play Jubilee to thin out your deck)
You've just played Mr. Negative no Iron Man in hand.
There are other circumstances but these two are the main ones where I Snap
Let's breakdown the card choices:
Sunspot: This deck tends to waste energy in the early game from lack of plays and the late game due to playing Negative cards which tend to have low cost. Sunspot is great for absorbing this energy. Combos well with Iron Man.
Angela: One of the best 2 drops in the game. You already know Angela generates a TON of value for her cost. Play her into the opponents Okoye lane to send a strong message to back off. -Angela isn't bad as a late draw either so long as she's not the last card you play into a location.
Psylocke: Lets you play Mr. Negative a turn early. One of the few cards that you really don't want to see in the late game. Even still, despite -Psylocke having underwhelming power, the extra energy can come in handy particularly when played turn 6 during Magik games. Going into turn 7 with 8 Energy has won me a few games. It's especially useful if Neither Iron Man or Mystique are inverted. You can play -Psylocke (and a bunch of other stuff) on turn 6 then finish up with Iron Man and Mystique to win your two lanes.
Mojo: One of the few 2 drops that doesn't become a bad card post Mr. Negative. Also he's an Ongoing with a pretty good effect that Mystique can copy in a pinch. Finally the psychological effect of Mojo on your opponents is really something and the more you play him the more you'll get a sense for how the card effects people. Early Mojo is "enemy card repellant". Your opponent will almost never fill out the Mojo lane so you can use that information when deciding which lanes you'll focus on and in the final turns when trying to guess your opponents moves.
Mystique: One of the essential card. This entire deck only works because of her and Iron Man. She does create an anti-synergy with Jubilee however in that sometimes Jubilee will pull her at inopportune moments and it'll likely lose you the game. ALWAYS know what cards are in your deck still and Snap (or retreat) accordingly. One thing to note is that if you Iron Man -> Jubilee and Jubilee pulls Mystique she'll copy Iron Mans effect since Jubilee doesn't count as "played" until after Mystique's On Reveal resolves.
Nakia: The point of the deck is to win games with Iron Man into Mystique. Nakia helps by putting a lot of power on the board including by buffing up Iron Man and Mystique themselves. -Nakia is also not a bad play turn 5 or 6 (during Magik games). She fills a good role in being a strong play turn 3 when you didn't draw Psylocke into Mr. Negative.
Wolfsbane: an OK play on turn 3 but not the best with this deck. You want to play her late game and especially if she's been inverted. -Wolfsbane is a great pull late game.
Jubilee: Gives you one last chance to play Mr. Negative on turn 3/4 when he's not already in hand. Also lets you plan an extra Negative card which can bring you one step closer to drawing -Iron Man or -Mystique.
Mister Negative: Another of the essential cards. You almost always play him whenever you can. I've played him turn 5 in games where I didn't have Magik in play (ie turn 6 was the last turn) just so I could get the chance to draw -Iron Man. That said sometimes he's not the right play. Particularly if on turn 5 you have Iron Man and Mystique in hand and the game ends turn 6 then you probably just want to play Iron Man then Mystique and a 3 drop.
Iron Man: The last essential card. One of the best cards in the game in it's normal form. THE best card in the game when inverted. -Iron Man wins games. Don't let him get buffed by Nakia too? Yeah it's a wrap. You've won that location.
White Tiger: A sometimes awkward card that's REALLY good when inverted but only OK when normal. Useful for putting the Tiger in locations you otherwise can't play cards in such as Sanctum. Good for filling the board with locations like Kamar Taj. Has synergy with Mojo. Has anti-synergy with Angela (the tiger spirit landing in Angelas lane doesn't give her a power boost).
Magik: Extends the game giving you yet another turn to try and draw -Iron Man or -Mystique. If I drew Iron Man and Mystique before I played Mr. Negative then I tend to play her on turn 5. This is so that I can play a 1 drop and Iron Man on turn 6 and then start turn 7 with Mystique.