This was done waaay back in 2009 in colored pencil. I distinctly remember trying in vain to draw this while on a train.
Here's an excerpt from my deviantART regarding the piece:
"This was a really difficult concept to get out of my head and into paper. No matter how many times I'd sketch it, something would end up going wrong. Once I had the phoenixes down, the colors for the pair were an entirely new battle. Finally, the background made me art-blocked for a good couple months until I finally finished it. But finally! It's here! And I never want to draw another leaf again!"