After playing this more, I made some changes swapping some stuff I originally had in my sideboard. The deck isn't heavy on the mites anymore and has more of a focus on using Veil of Assimilation and mite generation to buff up other creatures. Get out at least one Veil of Assimilation as soon as you can, spam mites to trigger it's ability on Mandible Justiciar or something with flying, use Atraxa's Skitterfang to give Mandible Justiciar flying or another creature lifelink and swing. The deck is pretty artifact creature heavy so this has been working really well so far.
I had to add some control so I threw Ossification, Planar Disruption, Surge of Salvation and Annex Sentry in there as well as added a few to the sideboard.
Most spells in the deck are phyrexian so it made sense to add Phyrexian Vindicator, Phyrexian Sensor, and Elesh Norn (plus I just love them), all of which have been successful in disrupting opponents. I plan to add another Elesh Norn at some point. The biggest issue I've had so far is obviously, if someone can destroy Elesh Norn or Vindicator they will, that or take control of them. The later has only happened twice so far (both times with Vindicator), but I still haven't gotten to play this deck a ton. Regardless, twice is too many. Very open to suggestions on anything I could add there to prevent those things.
Mondrak, Glory Dominus is definitey something I want to add, I just haven't been able justify the $20-30 on it yet.
Mite (heh) remove a couple plains to make room for Mondrak and another Elesh Norn as 23 lands has seemed like a bit much for this deck.
