Simple but very effective. I like it (y)
But actually i prefer the preview more.
You don't need to upload a detail image if it's the same as the preview file. The detail file is optional, and is only needed if your piece is too big to fit as the preview.
I quite like these animations! The shield movement in particular is a nice touch. I think it would benefit from a duller background that has a darker or lighter value though, as-is it's so similar to the colours of the character that they blend together, making the animation hard to see without zooming in. You could also just make it transparent.
amazing stuff