I needed a new weapon and haven't been getting any good weapon drops lately, so I dropped 99 cents on the Croc 2H weapon in the iTunes store.

I'm liking it, but what exactly is the Nightmare proc?

I'm hearing a screaming sound on occasion, but I have no idea what affect it has on the target (if any).

Anyone care to clear this up for me?

I'd like to know if it's a debuff, if it stacks, and the duration if possible.

TY