Im glad you picked up on Mabek, theyre inspired by Ammit in egyptian myth :D. Swap team is one of my favorite concept builds, but Seras is def weak in its first stage(maybe too much).
I still don't know what to say about weak or strong, regards to it. I need to study the combinations a little. I don't particularly like its design, in the first stage, because it's just a snake and it's weird in the middle of all the other cool/weird ones. Its evos look cool though!
I will try it more and, with the others, I will give my humble feedbacks during the journey. Congrats again man, I think it's absolutely my favorite game on itch, and actually one of the coolest roguelike I ever tried (and I played a lot of them).