I don't think this mix of Control Slaver and Mono U is as good as one of the original builds.

With the lack of Powder Kegs or any other Removal/bounce, there is no way in the MD to deal with Welders, Lackeys or what ever else may come in the early turns.

Against fast combo decks Chalice of the Void or Arcane Laboratory might be better than Stifle.

And I don't think this deck draws and tutors enough Cards to run Welders. 4TfK are to less to make sure you get the Platinum on the table against FCG or other fast Aggrodecks.

I don't know how your meta looks like, but for me it would be too risky running this Deck that only seems to do well in the Control matchup.

What about Mystical? What about Intuition?

-4 Ophidian

+ 2 Intuition
+ Mystical Tutor
+ Lava dart/Triskelion (?)

Or 2 Deep Analysis instead of Mystical and Dart.

Something like that.
Maybe cutting a Fetchland for Strip Mine.