Yes any stock in deviantart (as long as it's put in the stock categories) can be used in your artworks as part of photo manipulations! Then you can have different types of stock depending on the specific sharer of that stock, they all have different rules, so everytime you use ones stock just read under the image your picked or in their journal what rules they have for their photo. Unrestricted stock means that as long as you use the photo as part of a design or manipulation and that you credit the stocker (me) where you can, you can then use your artwork for any commercial or non commercial plan, no restricitions!! You can always read more here: FAQ #217:What are "Stock Photos" and can I use "Stock Photos" in my submissions? and FAQ #81:How can I make links to other deviants, deviations, or websites? about stock use and linking/crediting! Good luck!
Greetings! You have stunning stock. I loved this piece so much that I used it to create a piece called Magickal World Inner Sanctuary: [link] and I just want to thank you for letting the artists of Deviant Art use your stock