Just because you don't know how the mechanics work, doesn't mean we don't. Tempest does unavoidable damage on spawn. The only thing you can avoid is the splash damage by not stacking with too many other people.er
As for Archimonde, you're in a 1200ish guild, so don't spout "to cover up mistakes" shit. Now, I may not be in a top top tier guild myself but I did see the fight prior to ilvl upgrades (and of course after them), so it's not like I'm just spouting random shit. You could very well survive chain+wrought chaos with just barkskin, unless you fucked up or went out of range (or your healers were incompetent - relatively speaking) . A well-timed barkskin covers 2 wrought hits (the first is kinda irrelevant since it comes before the chains) and the majority of the chain. Sure, it doesn't cover all of it, but it does cover the majority of the damage you take.
I am not trying to argue that boomkin's defensives are top tier (because they aren't), just that you probably used the wrong example (and you exaggerated there, talking about externals+bear form).