0 CMC
Mishra's Bauble: A surprisingly integral card in the deck. It adds another card type, helps smooth our draws when used with fetchlands, let's us know what is going on for our opponent, turns on revolt, etc. The card is versatile.
1 CMC
Fatal Push: Easily the best removal spell in the deck and one of the best in the game.
**Inquisition of Kozilek**: Thoughtseize's little brother, helping to ensure we dominate the early game.
**Stubborn Denial**: The spell to replace Lightning Bolt or Path to Exile in sultai. While it doesn't fit quite the same role, it makes up for it by more easily dealing with things like planeswalkers and enchantments that the other BGx decks can't touch on the stack. Currently dropping the number in the deck to deal with a more creature heavy meta.
**Thoughtseize**: Helps tear apart out opponent's gameplan while simultaneously letting us know what we are up against.
**Traverse the Ulvenwald**: An extremely efficient tutor. Helps us find more threats, fixes our mana, and can even help us push through some final damage by finding Creeping Tar Pit. Early game it can allow us to keep a hand with fewer lands than we had hoped for.
2 CMC
Abrupt Decay: One of the best catch-alls at our disposal. Hitting pretty much everything in the format makes the card potent, and having the uncounterable clause pushes it over the top.
**Cast Down**: There are many conditional two mana black removal spells. This one from dominaria seems to hit the highest number of things we normally could not.
**Grim Flayer**: The keystone creature of the deck. His filtering ability helps us in more ways than one. He fuels our graveyard by being a big trampling beater.
**Nissa, Steward of Elements**: Usually we play her on turn 3 or 4. Testing out her viability right now but she seems good. More topdeck manipulation and allows us to drop threats for free. Her ultimate is also relatively easy to get to, finishing the game pretty quickly when the oppponent does not have fliers.
**Scavenging Ooze**: A great little creature that almost always ensures we have a threat to play on turn 2. Grows over time and provides incidental graveyard hate maindeck.
**Search for Azcanta
**: A fantastic way to filter our topdecks while simultaneously evolving our graveyard. Late game it flips, allowing us to dig for the last pieces we need to close out the game.
**Snapcaster Mage**: Really the reason why we play blue. He allows our used spells to always be online, giving us the specific answer when we need it.
**Tarmogoyf**: The big boss himself. We can build him up to be a 7/8 on our own maindeck (8/9 with bitterblossom in the board).
3 CMC
Liliana of the Veil: The queen of black herself. Time and time again has been shown to be just as powerful as she's made out to be.
**Liliana, the Last Hope**: The new Liliana on the block. Having the ability to kill something by with her plus, recycle creatures with her minus, and just about win on the spot with her ultimate. These things definitely earn her a a place in the deck. She's made all the better now that you can have her and LOTV out at the same time with the planeswalker rules change.
**Maelstrom Pulse**: The deck's true panic button for when we just need something gone.
**Rhonas the Indomitable**: Testing him out as a resilient 3 drop threat that helps us push through damage late game. He also pairs well with the rest of the deck with his condition being having psuedo-ferocious.