Welp, I finally finished this project; here is a link to the topic in finished works: Mermay 2023
Post-Mortem:
First of all, I'm still having difficulty gauging how much time a drawing will take; I didn't start as soon as I should have, but I also keep forgetting that life still happens even when you have a deadline to complete a project.
As for the final drawing, the usual caveats about how it's still kind of rough and not entirely what I was envisioning apply, but overall I'm happy with how it turned out; I'm especially satisfied with the contrast between the light and dark colors. I do think I was a bit too ambitious; even with a full month for the project, I went too far outside of my comfort zone to get it done on time. Learning to draw ocean waves in particular was a lot more difficult than I was expecting and I wasn't even going for a realistic look. I do like how they turned out in the end, though they are still more rough than I would like them to be. Same goes for the lightning effects, but they were much easier than the water. I also decided that I needed a 3D model reference for the staff, so I stopped in the middle of drawing and learned a 3D modeling program (Daz 3D's Hexagon editor); probably not a great idea when on a deadline, but I'm glad I did it. Having the reference model definitely helped and I plan on creating more of my own reference models in the future.
All in all, I'm glad I participated in the challenge even though I wasn't able to actually submit my entry; the things I learned along the way will certainly help with my own personal projects.