The Mind Cube- https://cubecobra.com/cube/list/mind_cube
The Body Cube- https://cubecobra.com/cube/list/body_cube

This is the Soul Cube, the second cube in a trilogy of cubes along with my Mind and Body cube. If you are a crazy person and have a bunch of crazy friends, draft it as I intended- as a team draft with each team sending one player to each cube for a Winchester, then playing each player on the other team. Hopefully the limited environment works perfectly fine both that way as well as a standard draft or sealed, but at it's core the most important thing about the cubes is that they are exclusionary- if a card shows up in one cube, it won't in the other two.

The Soul Cube in particular is designed to utilize the graveyard as a main resource. Consequently, expect to see flashback, embalm, unearth, disturb, self-mill and all sorts of nonsense. The power level on this cube is intended to be competitive with the other two, but with the operating space being "graveyard synergy" the Soul Cube might be a little stronger overall. Only with deliberate playtesting can this be determined.

There is a defender subtheme at the moment; it isn't critical to the underpinning of the main mechanics of the Soul Cube and so might be cut for more synergistic things moving forward, but I think it's easy to overload on one type of synergy in a cube and accidentally buff the power level too much, plus I think the defender package plays relatively well if you support it enough, so I wanted to try it out.

With that out of the way, a basic primer for the colors-

White:

White has a reasonable amount of cycling synergy, useful for a cube attempting to reduce RNG in a fun and interesting way. Because most opponents are going to have access to either a lot of life gain, a lot of creatures, a lot of synergistic graveyard components or maybe all three, standard mono W aggression is probably out the window, but White gets a lot of reasonable tools to help combat this. Lots of fliers, lots of ways to get around removal via disturb/embalm etc., and two of the most messed up cards in the cube are in white- Prismatic Strands and Akroma's Blessing can be plain stupid if you set yourself up well for them.

Blue:

At the moment, Blue might need a couple of more spells to help out spells matter, but that's not the main event here. Blue is self-mill and enemy mill, if you are brave enough to run it in a graveyard environment. But boy howdy, there's a lot of mill in blue. Blue also has a bunch of disturb cards to help pay you off for self-mill, but be careful as you will also get access to a lot of card draw. I really hope someone loses a game from milling and overdrawing themselves, that would make me inappropriately happy.

Black:

Black also runs a lot of self-mill, but instead of a bunch of card draw, we of course have reanimator and flashback and core components of the color. Black has what appears to be some weird anti-synergy going on, with some random X/1s and defenders running around, but as anyone who has played limited can tell you, a 3/1 can block a lot of different threat types fairly well. Black will likely play out as value-oriented as possible, and subsequently aim to slow the game down a lot, so I've intentionally tried to keep two-for-ones away from them whenever I can so this isn't just the Black cube, but I expect the color to be pretty strong regardless.

Red:

There's a Burning Vengeance and some Planeswalkers in there, so you know what that means- if you want to make a value-engine Red deck, hopefully you'll find you have enough tools to do so! I think it still benefits an environment if there's a fun police running around, though, so red still has lots of aggressively costed attackers and ways to really punish stumbles out of your opponent. Do note, however, that Burning Vengeance doesn't trigger on every graveyard mechanic, but it should still have plenty of food for the fire if you draft around it.

Green:

Green's ramp game might honestly be overloaded at the moment, but hey, if you want infinity mana maybe you can get some good value out of it. Overgrown Battlement and Axebane Guardian both need a little support out of another color if they are really going to go off, but fortunately there's some brown defenders running around to help whatever nonsense they are doing. Outside of that, of course, Green is doing big stompy things and self-mill and graveyard synergies as you might expect.

Gold/Artifacts/Lands:

As a consequence of a little bit of delirium running around, I've made a deliberate attempt to beef up the number of artifact creatures. The inclusion of Myr also means slightly more non-green fixing, but given that green isn't really just fixing but, rather, going bananas on ramp, I felt like brown fixing wasn't cutting into Green's slice of the pie too much.

Gold cards do what you'd expect, mostly, though there are some important cards to highlight. We, of course, have spider spawning, but I also like Psychatog and really hope that Zenith Flare isn't going to be nearly the problem in this cube that it was in Ikoria.

Due to my desire not to duplicate cards in any of the cubes, the mana is going to end up being a little wonky in places, and our lands and fixing kinda highlight this. Allied colored lands are better due to the sacrifice ability, but hopefully I've balanced this out by including more wedge mana support than shard mana support. I think, ultimately, the exact nature of your fixing matters less overall than the overall density of it, and I think we honestly might have slightly too much at the moment. We will keep an eye on this. I really like the Panoramas and New Capenna lands, though, as they play quite well in my basic peasant cube and that's without nearly as much graveyard stuff going on.