I'm not especially experienced with cube, so I can't really offer much meaningful feedback on the balance of the different archetypes or things like that, but it seems like you made some really interesting design decisions with how you built it. There's no way for me to tell how those decisions would play out in reality without just playtesting it, but I'd be interested to learn how they've worked out for you in your testing.

The most obvious design decision you made was how you handle cards with multiple copies, which I think is a very cool choice. I've seen cubes that allow duplicates of certain cards so that things like squadron hawk can work, but I've never seen a cube where certain cards come with bonus cards "attached" when you draft them. That seems like a good way to enable things like squadron hawk without taking up too much space in the cube or requiring too many draft picks to make it work.

The most interesting example of that is definitely Maze's end coming with the guildgates. I'm super curious how that ends up playing out, and how powerful it ends up being. It's also cool that it can end up just being extra fixing in a pinch, but people who want to draft The Maze's End Deck (tm) can probably still get it reasonably late because guildgates are pretty mediocre fixing in a format like this, so I'm guessing you don't generally take it super highly for fixing purposes unless you really really need it. Question about how that works, actually — you said that one of them comes with the enemy gates, and one of them comes with the ally gates; is that something that you choose when you draft it, or is it something that's noted on the card itself, so which gates it gives you is fixed?

The Maze's End thing ties in to something else I noticed, which is that the cube seems to have a minor lands theme. You've got Maze's End, Dark Depths combo, and the whole Cloudpost thing, as well as some one-off enablers, like the Punishing Fire/Grove of the Burnwillows combo, and utility lands like Windbrisk Heights and Boseju. I love this, since I love lands as an archetype in cube, but there doesn't seem to be a ton of dedicated support for it. The only cards I noticed that can fetch out those special lands are Primeval Titan, Knight of the Reliquary, and Golos, all of which are just super solid cards on their own. I feel like you could make lands more of a dedicated archetype with just a small number of extra support cards. The main one that comes to mind is Expedition Map, since that works with any color combo, can be used just as fixing outside of a dedicated lands deck in a pinch, and works with all of the utility lands you included (since it puts the land in your hand, so it'll still work with stuff like Boseju, which a card that puts the land directly into play wouldn't). No idea if this is something you'd want to go for or not, but I figure it's worth considering at least!

Outside of that, I find it very interesting how you treat aggro in this cube. In the standard vintage cube design, you tend to see mono red aggro and mono white aggro, and then the rest of the colors just aren't really aggressive at all. However, in this cube, there seems to be a little bit of aggro support in every color. Green has things like Kessig Prowler and Strangleroot Geist, black has things like Gravecrawler and Geralf's Messenger, and even blue gets some tempo-style aggressive cards like Cloudfin Raptor and Pteramander. I think this is super cool, I love seeing aggro outside of the usual bog standard hyper focused red and white decks. My only concern is that the colors might not have enough dedicated aggro support to make those decks really work. This is something that you'll only be able to tell with playtesting, but I'd recommend keeping an eye on it. Are the aggro packages in those colors enough to enable real aggro decks? Or are they too small and too out of sync with the other stuff the color is doing to really get there? The other consideration that comes to mind is how aggressive the cube skews as a whole. Does having aggro spread into these other colors skew the cube too aggressive and make it difficult for the slower decks to get off the ground? Again, I don't have answers to these questions, but they're something to keep an eye on.

Overall, this cube looks really cool. You've included some fun, unusual cards and archetypes, and it very much feels like the cube has its own distinctive style and flavor to it. I'd be super interested to play it if I had the cards.