Onderzeeboot
Ecstatic Orb
By the way, one of those customs was created to complete a cycle that is currently exclusive to the allied color pairs. These are great, great cogs, and I believe any low-power cube would benefit from adding these.
You should use your cube blog to stream of conscious your ideas. We can act as a whiteboard for you to bounce off of, and hone them. Even writing to yourself can help you hone and articulate them better.
Ideas are seldom perfect in their first form, and usually requite a gestation stage to reach full maturity. I don't think anyone here is going to attack you for presenting an unfinished product to talk over and refine.
Guided Passage was recently features in a legacy deck video series by Andreas Mengucci. He does great videos on the format, if you can get past the accent (which has drastically improved since he started making videos, interesting to watch them from that perspective) then you're in for really cool content regarding legacy.
Guided Passage seems super super time consuming on resolution. Reveal the cards in your entire library? The whole thing? Opponent then finds three cards (each with a set of criteria) and essentially gives them to you? That's like a 15 minute spell. It's fine for online Magic but with physical cards that sounds brutal. Weren't people complaining about Gifts Ungiven taking too long? This is way worse than that.
Why even play magic if your turns aren't going to take half an hour?
Both players start with an emblem that has Chains of Mephistopholes' oracle text, and once they hit five life are given a Teferi's Puzzle Box.
Are we sure withdraw is low power? That is a super cheap ultra tempo raping card. Don't under estimate that. It's really strong.
I'm kind of amazed there's this 2-->6 curve of "Bounce two creatures" spells throughout history