Cool idea i like it.
A1
B2
C2
E1
D1
^If any of the number letters matter to pick an interest for the viewer to respond to ^ those are mine.
In D2 if attacking low it seems his head would get engulfed in his own power/flames.

I think A2, C2, and E stand out to me the most. Like the concept, can't wait to see where you take it!

E variant looks simple and interesting at the same time, reminds me an alive candle
love it, good luck!

really neat thumbnails! you've got quite the eye for design