I was getting to a closer list, but then I worked in Overmaster x3. I really like the idea of a cheap disruption, and at a minimum it cantrips. That gives us up to 12 straight cantrips that are mana efficient (Manamorphose, GitProbe, Overmaster.) I found in so many situations the real hitch was resolving a payoff spell (Burning Wish, Past in Flames, Reforge the Soul, Hazoret's Undying Fury.) Also, with Overmaster main that means I can cut sideboard copies of Pyroblast (which are good, but not great) for additional spells that can do a lot more work (Abrade, Ensnaring Bridge.) Current list with sideboard:
Rituals - 114x
Rite of Flame3x
Desperate Ritual4x
Seething SongArtifacts - 104x
Lotus Petal4x
Ruby Medallion1x
Helm of Awakening1x
Chrome MoxDraw - 64x
Manamorphose2x
Act on ImpulseDisruption/Peek - 73x
Overmaster4x
Gitaxian ProbeStorm Engines - 53x
Past in Flames2x
Hazoret's Undying FuryTutors/Win Conditions - 74x
Burning Wish2x
Gamble1x
Empty the WarrensLands - 1410x
Mountain4x
Crystal VeinSideboard1x
Past in Flames (wish)1x
Empty the Warrens (wish)1x
Tendrils of Agony (wish)1x
Grapeshot (wish)1x
Cave-In (wish)1x
By Force (wish)1x
Reforge the Soul2x
Blood Moon1x
Tormod's Crypt1x
Ensnaring Bridge2x
Scab-Clan Berserker2x
Pyroblast
So far, the extra cheap cantrip of Overmaster has been better than feeding countermagic to opponents with Wheels. I love the 1-of Wheel in the sideboard, but maindeck it is just too risky. Much happier with Act on Impulse, which I would love to get a 3rd copy in there. I will test for a good amount of games, probably 20 or so, and then see which card can be cut. Preliminary ideas for the cut would be the Chrome Mox, a GitProbe, a Desperate Ritual, or the Helm of Awakening. Everything else seems to be necessary for me. I won't budge on the 2 Gambles because they are ways to functionally get my 1-of non-BW sideboard cards g2-3.
@mistercakes: you somehow omitted Gitaxian Probe in your most recent post of potential cards.