shadows and void are the same thing. gloom blade, goremaw's bite, that sub dot that slows, the damage buff/energy restore ability you use while stealthed, cloak of shadows, and stealth itself.
stealth isn't just camo, "Conceals you in the shadows until cancelled, allowing you to stalk enemies without being seen." is the direct quote of the tool tip.
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it's void, because we can look to shadow priests next patch.
all of their spells use "shadow" magic, yet they get whispers with every one, just like void.
i thought there was a difference for a while, but now it's clear that shadow is just a more religious idea of the void.