While the previous post was somewhat informative as to the nature of +damage items, my question is really to the benefit of -spell resistance items, referred to by many as "penetration". How does spell penetration work, and why is it a goof thing? Will I see a benefit by stacking -spell resistance gear?

By the way, the staff does proc on corruption. It hasa a chance to proc on any spell that successfully lands. The proc rate is pretty high--I seem to get one about 15-20% of the time.

Finally got a decent weapon... My fang of venoxis was long overdue to be replaced. As I already have some -resistance gear (two pieces of doomcaller), and CoS on, I can safely say that there are no negative resistances at all, that rumor is false.

It gives you a buff, Mystical Disjunction, which gives -50 resistances to your spells to your target. You do not need to keep target the same, you can switch targets while the buff lasts and it will still produce an effect.

It didn't seem to proc from any AoE I did, but it procced from curses. My guess is that it would proc on Corruption too, probably on a cast, and not a tick... I don't use corruption tho as I'm MD/Ruin spec.

It seems to proc irregularly, at least to me. When I got it, I got procs on my first shadowbolt on all the mobs in first two packs. Then it didn't proc at all till next boss. It continued to behave in this manner - that might have been only my luck though.

I like this staff :)