I’m not sure about abilities changing the role of a spec, but under those circumstances, change Ebon Might into a buff that procs a bit of damage instead of providing primary stat and attribute the damage back to you with a big aggro bonus attached. Then tanking becomes both needing to damage enemies and maintain Ebon Might to hold aggro. Throw in ‘Obsidian Scales provide 100% spell pushback resistance’ and you got a weird but interesting way to tank.
Like you said, did have to type ‘advanced’ after all.