Legion Loyalist is abetter 2-of, he is more of a combat trick than a 1 drop. I think Experiment One would do you some good. I would definitely look into adding those Mizzium Mortars, that card took my american midrange from crap to winning tournaments. 2 domris should be plenty, but I also realize that they might not last on board as long as you would like. I know this guy jumped up ridiculously recently, but Huntmaster of the Fells  ^Flip would be a boon in this list, especially since zombies might make a comeback (BW versions). See what 3 drops you could add as well, your curve is a bit interesting, Wolfir Avenger is nuts and a great card for control, I do not think you need the simic leader and craterhoof seems a bit heavy to play in this list. If you feel you need some replacements, I got a list of cards that goes for days of stuff you could play in this deck, the problem would be maximizing the synergy, which would require playtesting a lot. I think though you just max out at the Thragtusk and maybe a Thundermaw Hellkite or two (like a 2-2 split?).

Experiment One was actually my first choice over Legion Loyalist, but my local shop didn't have any. Same goes for Wolfir Avenger.

In the last FNM, Mizzium Mortars felt like a dead card more often than a good one. the only times I felt like I needed it, it would have been for Boros Reckoner, but 2-for-1ing myself doesn't seem like a good idea, especially in that match up because my board presence is more important than ever.