+1 for sheer brilliance! I'm actually mad that I've never come close to making a deck like this. Prescient Chimera is the only card that I can think of that might benefit this deck, though maybe more so in a sideboard vs. decks that go mid- to long-range. Check out my noble deck: Noble Urborg - What the FRACK?! [Drillin' for Oil]

Crap. Obviously you've seen my Urborg deck. Disregard the last sentence of the post above. My bad.

Prescient Chimera can be good, but i don't think i have enough instant/sorcery for it. And it cost 5 to play. With the Prognostic Sphinx as noble (i still not sure if i prefer the sphinx or Thassa), i would prefer to play the Sphinx instead of the Chimera.

Thx for the comment and the vote! It's very appreciate :)

Serum Visions seems more on-theme than Brainstorm here. Brainstorm is insane in older formats because of the prevalence of fetchlands, which let you reshuffle away two cards for virtually no cost (making Brainstorm into something close to Ancestral Recall). Even without shuffle effects, it's possible that Brainstorm is still better than Serum Visions, but the lack of scry seems odd.

Where are the control elements you mentioned? All I see is Scouring Sands, which I'm not convinced should be played in mainboard.

If you want counterspells, Condescend works fine, and Mana Leak might be better than Alexi's Cloak. Even if you only stop 1 spell with Mana Leak (as opposed to multiple that you could potentially stop with Alexi's Cloak) the shear flexibility of Mana Leak might be worhwhile.