I love this depiction of Azrael! I put all the details of my thoughts regarding it under my comment for the front cover version of this painting, so here I will suffice it to say that it is simply the best and for me the most definitive depiction of this particular angel like ever. It is cool seeing more of the amazing background here, too! Lots going on there, with many elements that come together nicely... hellish elements, heavenly ones, and a hint of the post-apocalyptic that jives ideally with the Angel of Death and her nature. Brilliant work!
Thanks! I usually don't use exact references but most of the time i gather a few different photos for inspiration: mood, light, textures, face expressions etc. As for the tablet, an older Wacom Bamboo (i think the newer versions are not called like that anymore).