If you don’t know, unlike previously CMC of split cards is now the sum of the two parts. This was done due to the abuses on older split cards with cards like [scryfall]As Foretold[/scryfall] and the different Expertises (mostly [scryfall]Kari Zev’s Expertise[/scryfall]). On the other hand, there are cards that like your cards being expensive.

There’s two split cards in Amonkhet that seem strong here.

[deck]
[creatures]
4 Combustible Gearhulk
2 Noxious Gearhulk
[/creatures]
[spells]
2 Liliana, the Death’s Majesty
2 Ob Nixilis Reignited
3 Sorin, Grim Nemesis
2 Nahiri, the Harbinger
3 Painful Truths
4 Never // Return
4 Cut // Pieces
4 Tormenting Voice
4 Fatal Push
[/spells]
[lands]
4 Inspired Vantage
4 Concealed Courtyard
4 Shambling Vent
4 Needle Spires
4 Evolving Wilds
1 Plains
3 Swamp
2 Mountain
[/lands]
[/deck]

The manabase definitely sucks and would require some work. Actually a lot of work.