I would fight Discord. And, I would win.
I wouldn't use physical force, magic, firearms, or any other conventional strategy. Discord is, easily, one of the most powerful forces in Equestria. A normal confrontation would be simple suicide.
I would outwit him. While Discord has a great deal of raw power, his power makes him sloppy. He dramatically underestimated the capabilities of the Mane 6.
I would confront him directly, and I would use the power of rhetoric to somehow get him to incapacitate himself. This is a fairly time-honored tactic for taking on arrogant, reality-warping entities.
Of course, if by some off chance I don't win, then I would get brutally annihilated in a flurry of low comedy. A suitably epic if somewhat humiliating demise.