Wurmcoil Engine is a solid creature for this deck. Expedition Map would help you with tutoring for a utility or ramp land. some ramp artifacts that produce colored mana are Chromatic Lantern, Moss Diamond, and Charcoal Diamond. If you add more mana rocks it would help your affinity cards. Can make room for these by cutting land down to at least 40 in my estimation. Toxic Deluge is a solid sweeper and Languish might come in handy. +1'ed

Attrition + Ornithopter

Dare I say Blightsteel Colossus?

It certainly would win games, but I really am not fond of infect. Alos, the colossus would draw a lot of hate at the table, and it can only kill one person at a time.

I play Urza's Bauble and Mishra's Bauble in my build for some cost draw spells. Grismold, the Dreadsower is good for making sure your opponents always have some meaningless creatures to kill and trigger Glissa. I don't run it myself, but I've heard good things about Bolas's Citadel.