I run a very similar deck to this and found blue to be the perfect addition for cards like
Slip Through Space,
Artful Dodge,
Distortion Strike, and even
Ghostform to get damage through. You get access to cards like
Vapor snag to bounce blockers or problematic utility creatures and gets in a point of life loss.
Gitaxian Probe is also a great card to let you take a
peek and decide if now is the time to go all in and also cantrips so you don't lose tempo. You already mentioned
Serum Visions but
Telling Time and
Anticipate are great filter spells that let you sculpt your hand and trigger prowess. You also get to use
Twisted Image as a side board card to remove Walls,
SpellSkite,
Birds of Paradise and any other 0 strength problematic creature also if you decide to go with
Stormchaser Mage you can use
Twisted Image to make him a flying 4/2 before any other pumps.