support has 150 base hp I think, 200 with passive 2 and 250 with passive 3. I'm not sure exactly how much hp gold armor adds but I'm guessing it isn't enough to put support hp over 400. overhealing gives you 50% more hp so 600...idk, that does seem like a lot of damage, but I think honestly an assassin should be able to kill everyone with a level 3 backstab except a very hefty tank or gunner