Cephalids, Xirn and U/B Identity in Overgrowth

So I was very, very disappointed that cephalids not only didn't appear in Dominaria at all, they aren't so much as referenced in flavor text or even in the story. It's not even clear if their kingdom still exists (and Mark Rosewater was typically cagey about when asked). There's still merfolk, but we don't know of their rivals are still around.

So for our participatory version of GDS3's tribal challenge over at Goblin Artisans I picked them to try to iterate a concept of how I actually want cephalids to play in Overgrowth. I technically picked "octopus" as my tribe. I'm taking a page from the way Wizards of the Coasts deals with avens and khenra from Amonkhet and referring to them by their animal roots rather than their race. Octopuses are a recognized creature type. Cephalids are not.

I am actually pretty happy with how the exercise turned out. And while I don't intend them to be played as a "tribe" in Overgrowth like the challenge required, the exercise helped me figure out the goal for U/B gameplay. It draws on black and blue's shared interest in manipulating cards outside the battlefield and playing cards from places other than the hand. And even from playing opponent's spells. We're not going with the Amonkhet/Innistrad creature recursion method. But rather, reusing sorceries and instants or using your opponents' spells.

So here's my new "signpost" creature for blue-black.

In the tribal version, the damage scaled based on octopuses in your graveyard (I kept the desperate, disease-afflicted identity of them for this exercise). In this case, I want to go with a mini-drain. I may want to tweak the numbers based on testing. Since the concept behind gameplay is so control oriented, they need a way to gain life.

Speaking of control:

So if you cast Xirn's Rebuke and copy a spell and you have Blightcoast Reaver out, it will trigger the Reaver's life drain.

Figuring out what I want for the cephalids' playstyle also meant rethinking Xirn as a planeswalker:

Part of me thinks that +1 is too powerful, but have you seen Teferi?

(Edit: Just realized his ultimate needs to be able to use any color mana to cast the spells in order to work properly.)

Black's version of board-clearing in this set is also tied to the cephalids:

I need to be careful about black sacrifice outlets in the set. I currently don't have any. I'm sure there will be some, but I need to make sure they can't be triggered multiple times in a turn.

There's also going to be some design tension here between U/B and B/R. These guys want to reuse spells in graveyards. R/B wants to exile cards from graveyards to trigger effects. I don't want to pull black in too many directions because that can cause problems in limited. I think that's what's happening with red in Dominaria. Too many different play dynamics based on what color you pair it with and the creatures just don't synergize well. So red ends up being one of the weaker colors in limited formats.