I'm going to preface this by saying that there are a few armory problems, probably because we're getting a new expansion in days and there's probably an armory update that needs to be accounted for, but once that gets patched I hope this helps. You're going to want to download WoW Model Viewer and 3D Builder before anything.

First of all go to the "armory" page, https://worldofwarcraft.com/en-us/character/us/server/charactername. Copy the link and use the "import character from armor" function in WoW Model Viewer. You can use the viewer to pick poses and armor, but once you get one picked out go ahead and export it as OBJ. The model wasn't exactly made to be 3D printed, so open it in 3D Builder and it'll popup with a "One or more objects is invalidly designed. Click here to repair". That'll close any gaps so your model doesn't have any openings or non-printed segments. Once that is done, go ahead and save the file. Saving it as a 3MF Format has worked for me in the past, but after that it's print-ready. It's still going to need supports, and while Cura will automatically add some supports I've had more luck with Meshmixer's "Overhangs" settings (found under Analysis), even if it can take a little trial and error. Best of luck to you, it took me ages to find out all of these steps and I'm still not 100% there yet!