I don’t really know what to do here. I guess I want scrying to help with Keranos’s trigger, but how much of it do I want? Its probably safe to put quite a few into the mix, because they will be highly contested, efficient cards.

Keranos’s Two-Colored Cards

Sadly, there aren’t many UR cards that scry (well, two). I’ll just put random goodstuff here, then.

[scryfall]Stormcaller of Keranos[/scryfall] gets in for flavor reasons.

[scryfall]Stormchaser Chimera[/scryfall] is probably tied into Keranos somehow as well.

[scryfall]Winterflame[/scryfall] is just efficient removal-slash-tempo, so its in. Its not on par with, say, [scryfall]Lightning Bolt[/scryfall], but it does do stuff.

[scryfall]Quicksilver Dagger[/scryfall] might be too good, depending on how much removal there is in the set, but its definitely an aura that’s worth its cost.

[scryfall]Spellbound Dragon[/scryfall] seems like a fun effect. Never played it though.

Blue

[scryfall]Aqueous Form[/scryfall] is a nice card with quite a few big creatures, but its also the cheap and somewhat reliable way to get ongoing scry triggers.

[scryfall]Dissolve[/scryfall] is one of the better hard counters (obviously nowhere near on par with the original [scryfall]Counterspell[/scryfall]) with the scry attached.

[scryfall]Eyes of the Watcher[/scryfall] is another ongoing source of scrying.

I’ve always liked [scryfall]Fated Infatuation[/scryfall], even though I haven’t been able to use to effectively that often because of the heavy blue requirement. Despite this, its a good trick, which people don’t expect.

[scryfall]Mystic Speculation[/scryfall] is another source of scrying and with enough mana, it can be very good with some of the red cards below.

[scryfall]Omenspeaker[/scryfall] is just a cheap, efficient blocker with an upside.

Even Keranos needs bodies, so [scryfall]Prescient Chimera[/scryfall].

[scryfall]Divination[/scryfall] is in just because the Theros-version (or Born of the Gods, to be precise) is Keranos-flavored. Its still pretty good, but probably not good enough for the cube longterm. It is also a sorcery, which is nice with some cards on this list, keeping this from being strictly worse than, say, [scryfall]Mulldrifter[/scryfall].

Red

Because just scrying would be boring, here’s a card that can benefit from those in a nice way: [scryfall]Flamespeaker Adept[/scryfall].

Here’s another: [scryfall]Knowledge and Power[/scryfall].

[scryfall]Magma Jet[/scryfall] is good removal with scry. No question here.

[scryfall]Sigiled Skink[/scryfall] isn’t quite good as you’d need for the cube, but its okay.

The cube is lacking in tricks, so maybe [scryfall]Titan’s Strength[/scryfall].

[scryfall]Brutal Deceiver[/scryfall] doesn’t quite scry, but is more efficient, if you can scry often.

[scryfall]Galvanoth[/scryfall] gives you an edge for being able to scry. Getting even one spell off is pretty good, getting two spells is really good.

[scryfall]Goblin Spy[/scryfall] is pretty poor, but seems like fun. At least it tells you when to use that scry-effect.