What to do with this? There aren’t too many worthwhile X-spells in these colors. Some card draw, sure, and hydras, but putting 21 X-spells into the cube seems like an awful idea. So, I’m going to just put fun cards here. And UG does have some of the best of those.
Since I don’t have any real theme here, I’ll go with morph, since I like that theme very much after playing plenty of Khans draft.
Kruphix’s Two-Colored Cards
[scryfall]Unexpected Results[/scryfall] is best of the best, when it comes to fun.
[scryfall]Urban Evolution[/scryfall] isn’t fun in the same manner, but it is good.
[scryfall]Species Gorger[/scryfall] is one of those cards with downside, you can “cheat” into being good.
[scryfall]Sagu Mauler[/scryfall] and [scryfall]Icefeather Aven[/scryfall] go well with the morph theme.
[scryfall]Nimbus Swimmer[/scryfall] would be nice, but its also quite boring.
[scryfall]Plasm Capture[/scryfall] could actually be a card that has good synergy with Kruphix. At least a little bit.
If mana burn rule wasn’t lifted (and its a good thing it was), [scryfall]Pygmy Hippo[/scryfall] would be fun.
[scryfall]Sharless Agent[/scryfall] would be great, but well above budget restrictions.
Morphs: [scryfall]Pine Walker[/scryfall] and [scryfall]Hooded Hydra[/scryfall], the latter of which is both a morph and a great manasink.
[scryfall]Enshrined Memories[/scryfall] seems legit.
[scryfall]Genesis Hydra[/scryfall], [scryfall]Wildcall[/scryfall] and [scryfall]Vastwood Hydra[/scryfall] fill that quota as well.
I like green card draw more than blue (which is often pretty meh), so I’ll put a couple of those here: [scryfall]Hunter’s Prowess[/scryfall] and [scryfall]Soul’s Majesty[/scryfall].
Morphs: [scryfall]Fathom Seer[/scryfall], [scryfall]Kheru Spellsnatcher[/scryfall], [scryfall]Mischievous Quanar[/scryfall], [scryfall]Mistfire Weaver[/scryfall], [scryfall]Stratus Dancer[/scryfall] and [scryfall]Unblinkin Bleb[/scryfall]. Well, that’s six. Seems pretty good.
I’ll put [scryfall]Laboratory Maniac[/scryfall] here as well, because why not? Since we also need some card draw with that, I’ll put in [scryfall]Breakthrough[/scryfall], because I find it interesting.