Steel Overseer is definitely a great card for this. Another couple good cards: Grand Architect and Triskelion . Triskelion actually goes very well with the theme of the deck and can be a win condition on his own, as well as removal for multiple creatures. Academy Ruins also fits nicely in here, and does much the same thing as the Arcbound Reclaimer in your sideboard, but as a land. Suncrusher could be a giant threat, and he is very tough to kill. Finally, Fabricate to tutor up your artifacts, and Thoughtcast for some cheap draw power, since you will normally be casting it for U instead of it's regular 4U.

I had forgotten about Steel Overseer ! He was one of the cards I was thinking of adding while I was first making this deck. I'm not sure about Grand Architect because the added +1/+1 isn't a counter. The additional mana ramp is nice and it can grow very fast effectively doubling my mana...hmmm...I'll have to try it, but he could be a replacement for the Vedalken Engineer 's... Triskelion ...I like him. :D I could see Academy Ruins ...fills the place of two cards with one, but I don't know how beneficial it will be since only one could be in play at a time. :/ I was mainly looking at a theme of Modular for this deck, but many of the cards you've listed would benefit me greatly. Suncrusher is just a deadly card in general! haha If I do add any of these cards and deter from my Modular theme Fabricate and even if I don't deter Thoughtcast will help out a lot!

I'm kind of thinking of making this a mono blue deck again... Tezzeret, Agent of Bolas is a nice card, but I don't get to use him often enough to make it justifiable and with only one other card Grim Affliction benefiting from having black...I'm not sure if it was a good idea :/ haha. Grim Affliction is a helpful card and I do get to use it quite often surprisingly, but I'm not sure about the dual color. The only other benefit I can see is Arcbound Crusher gets more +1/+1's from Vault of Whispers ...I'll have to work on this! You've given me a lot to think about haha. Thanks for your input!

I think I'm going to add Triskelion for sure and also a Throne of Geth to make it easier to use my Modular creatures to buff him up! :D

I hate to do it, but I'm thinking the best thing to do is make this mono blue again and remove 4x Vault of Whispers , 3x Swamp , 4x Grim Affliction , 2x Arcbound Fiend , 1x Arcbound Overseer , and 1x Tezzeret, Agent of Bolas . I'll add 4x Steel Overseer , 4x Triskelion , and 7x Island . I also may remove 2x Fuel for the Cause and replace them with 2x Fabricate .