Cosima MUCOTK (pronounced muck-aught-cah I guess)
Approximate Total Cost:
I opted to omit extra turns in the deck, since Magosi seems funner and still potentially pretty strong with Rings of Brighthearth. Walk the Aeons is very on-theme but it's also such a drag to play against so eh. I went pretty heavy on theft, as a way to neutralize enemy commanders and just generally keeping people busy while Cosima is ticking up.
The thing that bothers me the most is how low the basic count is, considering the heavy focus on fetches, but then again it should be plenty to get to 21 power off pure fetches so maybe it doesn't really matter. It'd take a million to get Cosima to 21 twice, so if she does get killed in a freak accident I guess you'd have to win the slow way. There's an infinite combo with magosi, rings, and deserted temple, so you can chip in eventually for the kill if you can assemble that. But for the most part, you should be protecting Cosima easily, you're drawing 19+ cards AS she etbs, she's got free flash and essentially uncounterability when re-entering, so if you can't protect her then idk wtf happened but I think you might suck at magic?
Original post:
I like the new God design, but I think the one that I can most easily visualize as an interesting deck is Cosima, God of the Voyage. Specifically, what appeals to me about her is that after a single setup turn, she's basically impossible to interact with, and equally impossible to stop reentering and drawing cards at will. While she's mono-color, she's in the best mono-color for control as well, and a durable, powerful wincon is a huge benefit for a control deck.
So the game plan I can visualize here is pretty straightforward - play Cosima, exile her ASAP, and then play the game as a normal draw-go control deck, ideally keeping a fetchland available at all times just in case, to crack and draw a ton of gas. Obviously run as many decent fetches as possible (yes, including panoramas) to get double triggers every turn, if possible. Assuming she doesn't need to get cracked early, though, the plan would be to dump her to play EOT when she's a lethal attacker, draw a million cards to protect her, and then use either a way to remove blockers (cyc rift) or push her through them (rogue's passage) to instantly knock people out of the game with a massive, heavily-protected commander. Then, depending on the version of the deck and how dickish it wants to be, play an extra turn effect(s) and kill the rest of the table without giving anyone else a turn, or just rest on your trove of answers/protection and kill them one at a time.
I really like the omenkeel side of her, but I can't think of a good way to use it as a commander. If it was white, I'd just run it as a durable commander in a boardwipe deck, but in blue I can't think of anything really, there's only a couple wipes and they're pretty much all bounce-wipes. You could play a bunch of other vehicles to trigger the ability, but idk what the point would be, you're still only playing 1 land per turn, and they're not great lands since they'll vanish if the player dies. Could see it slotting into the 99 somewhere maybe, but as far as building a deck around it, I'm drawing a blank.