Debuff duration and stacking

[Superzarop]

How long do the debuffs like hell scream, crushing blow and nightmare last? I cant find them on discriptions.
And do the debuffs of same effects stack with eachother? Like can nightmare and hell scream be applied at the same guy at the same time? And does the 30 armor reduction of crushing blow stack with the hell screams crushing blow?

[Arterra]

i think the only (self) stackable debuff is break shot. otherwise they can all go together, they are not the same exact debuff.

[Superzarop]

Cmon havnt Royce tested the duration of these stuff?

[Ellyidol]

I just like to assume them lasting the moment you cast them until the moment it coolsdown. So spamming it keeps it on. I can't confirm though. As for stacking I don't know with break armor, but I know the rest don't stack themselves. So for a good group I'd look for debuff variety than debuff depth.