Probably the section of the deck most in flux, and I need to run some of the math on what's the exact number of white sources to splash in a deck that still wants to cast Cryptic Command. The current mana base gets the job done, though it's a little weak to Blood Moon. The card I've been continually impressed with though is Cavern of Souls. It's an incredibly powerful tool that can single handedly win games in the right situations. Not bad for a land. Between UWR, Twin, mono blue Tron, Delver, etc there are a fair number of counter spells in the format, and if you can slam a Geist of Gaint Traft into play Turn 3 or heaven forbid a Teferi, Mage of Zhalfir after sideboard it almost feels dirty. As one UWR opponent put it "You play Cavern of Souls?!?" as I slide my Geist of Gaint Traft into play in the face of his open mana.
The creature selection is pretty straightforward. Flash is a must since we want to hold up our mana on the opponents turn, unless it's simply that good like our friend Geist of Saint Traft, and being a wizard is a plus. Snapcaster Mage, Aven Mindcensor, Vendilion Clique and Teferi, Mage of Zhalfir can all be cast counter-free off of a Cavern of Souls on wizard. A lot of the creatures also get value for simply coming into play, so even if the opponent has removal we gained some advantage. The pair of Aven Mindcensor might get swapped out for a third Vendilion Clique and land 25, but I want to spend a bit more time with the current iteration before making more changes.
The bread and butter of the deck, combing the best counter spells of the formats with arguably the best removal spell. Remand and Cryptic Command are just really powerful for their ability to replace themselves, there's a reason why Remand is often jokingly compared to Time Walk. While it has its drawbacks which is a bit counteractive with Mana Leak, Path to Exile is just a much too efficient way to get rid of practically any threat. Finally, Spell Snare is an excellent tool for capping off a counter war or for tagging a 2 CMC spell when you're on the draw.
If I play Serum Visions enough I can pretend it's a better spell like Ponder or Brainstorm. Even if Serum Visions won't ever be as good as those cards, it does a decent enough job of fixing and informing our draw steps. We're not really a combo deck looking for pieces, but it's still nice to hit everything on curve or be able to dig when needed. When combined with the Scalding Tarn during Game 1 it provides an excellent way to throw opponents off the scent, making them play towards Storm or Twin decks instead. The miser Steelshaper's Gift serves as a third sword, which has the added advantage of being able to flashback with Snapcaster Mage if it's relevant. Sometimes it's effective simply to search and reveal out a sword and use it as counter bait to get something else through.