Seems pretty sweet!

Obviously your deck building philosophy departs quite a bit from mine, as I tried to build a relatively brutal and fast combo deck in contrast to your more midrangey build, but there are still some cards that I would suggest as far as cuts go. Although I would call myself an Izzet Chemister with pride, Mizzium Mortars never seemed to work that great for me. Why would you limit yourself to dealing only four damage? Even if you overload the bloody thing to achieve the "one sided board wipe" bonus, chances are that quite a lot of creatures your opponents have will survive it - it is commander after all we are talking about. Unconditional and versatile removal spells are king. I would also suggest swapping out a couple of your high end creatures for some more ramp spells. Your deck looks pretty slow, your average CMC is past four - that even surpasses my Kozilek, the Great Distortion deck, which mostly consists of huge eldrazis! The lack of ramp in your deck is staggering. I know that stuff like Cultivate is boring to include and I do not know how fast your games tend to be, but the more mana you have the faster you can deploy your threats and the more spells you get to cast! Casting one spell a turn is not what you want to do with Prossh. Prossh gets exponentially stronger the earlier you cast him, so the faster you ramp the better!Additionaly I would cut Shattergang Brothers, as they have no real synergy with the deck. You will only use the first ability, but the other two will probably never come to effect, since your amount of expendable artifacts and enchantmemts is pretty low. I like Butcher of Malakir way better if you are searching for attrition effects.

I hope that my thoughts are at least a little bit helpful, since I obviously have no idea what your playgroup or a normal game of commander plays out for you. Have fun tinkerig with Prossh!

Thanks for the suggestions! I went ahead and updated the deck to better fit my play-style. I'm still working on updating the description.

First of +1. I love Prossh builds. All things fall to the might of Prossh! I do have a couple suggestions for you. I agree with what TheDracogenius said. Ramp, ramp, ramp. Couple ways to do that would be add Skyshroud Claim and Xenagos, the Reveler ( I see this one in the maybe board. Also some tutors. If cost is an issue add Diabolic Tutor. Demonic Tutor and Vampiric Tutor are amazing. Helps deal with any threat. Lastly, the land base. Anything that comes in tapped isn't the most amazing. Unless your play group plays a slower style and you can wait a turn to use them.Strip Mine is always a good add just in case someone pulls a Gaea's Cradle or just has 1 type of land they are exploiting.

Happy building and resurrecting your Prossh, Skyraider of Kher

DasTree you forgot to hit the +1!!!! Thanks for the comment, some good advice there. I won't be adding Vampiric Tutor or Strip Mine because if I had them they'd go in a different deck. :)

Woops. thanks for the catch. I was busy at work trying to avoid the boss. [