I wanted this to be some kind of illustration to depict Celestia and Luna while they were still Queens together. An official portait or tapestry, something like that. I also wanted to incorporate a tweak I've made to A:TLA's bending system, indicated by the notes to have Celestia bending Air and Fire, and Luna be bending Water and Earth. Dual-benders exist, they're fairly uncommon, and only like seven triple-benders have existed in all of recorded history. The Avatar is still unique for bending all four elements.
Program: Clip Studio Paint
Tablet: Artisul D16
Time taken: unknown