Mastery: only good with AP?

[braxx]

Does mastery have any relevance outside the Agonizing Poison build?

In other words: would a exsang build with about 90-100% mastery be viable?

[Zederren]

You can sim yourself to find out. Even as bleed build, it's not too terribly bad for me (0.63 vs crit @ 0.75). It's sure as hell better than haste