Jeez! That description from TinneOnnMuin is such a strong kick the groin. It is so egregious.
Let me be clear because a player whispered me about this post. I shouldn’t have to explain this since it was plain english but…
TinneOnnMuin’s description shows that who ever messed with the code for this weapon went to considerable lengths to make it crappy. The effort put into the crappiness of this weapon is what I consider egregious.
Once upon a time Calamity was considered a BiS weapon when it applied marks to every single enemy hit.
I see no reason why they can’t change it back to how it was, its no where near as broken now considering all the other things that have been added to the game since then.
back in the days when marauder turrets auto-fired multishot and cluster arrow
I would buy the full priced expansion that reverted this build to its former glory. 
man, I’m always the last to know this stuff- I knew there was something wrong with my build, and this is it. Anyone else have the game get really jumpy and weird when you’re at top speed strafing, and there’s a lot of mobs on the screen? I find myself getting ported around, and mobs disappearing- you know, like the lag when the game was new. Doesn’t do it to me with any other set…
Just had a primal Calamity with perfect rolls drop… screams in Demon Hunter
(Forgot that primals are always perfect rolls)
It’s exactly the same that happened with the WW barbs since there was a “perma WW” build. Somehow the game is not very good at those fast moving skills I guess.
Just picked up a primal ancient and was hoping this was viable… 
Primal Calamity is a bit mixed blessing. At least the bug messing up GoD momentum stack gains was fixed.
However because how the the weapon behaves, it’s borderline useless. And since the damage bonus is additive, in the case of GoD its benefit is diluted by normal HA skill affixes, Taeguk gem (yes, that’s additive too), etc.
Yes, you would have to swap Taeguk for Zei’s and swap one of your skills for a worthwhile rune for Marked for Death.
Viable is a funny word though. Of course it’s viable. But I wouldn’t say it’s one of the best choices.