Well I think I may of found a possible exploit with Ice block, it may take some timing but some how I managed to take damage but then be able to pop iceblock and have full health as I did at the start
I'll try reproducing this by:
Get one shotted by a huge boss, e.g. Drek'thar in AV (where I found)
Pop iceblock just after he hits me, before I actually die
Full hp
As I said I don't know whether this is confirmed, or just an abuse of a laggy AV, either way it may benefit some people.
Please reply with confirms, i'll continue to test and give updates as I go.