Hello,
found it on some forum, I dont play DH myself yet but seems worth sharing:
With ranged weapons, it seems like critical hit percentage is tied to the projectile when you fire it.
Now, this doesn't seem like it should be game-breaking in and of itself, but DH's get two rather ridiculous abilities that allow it to become so.
The first is "Sharpshooter", a passive that builds up your critical hit chance (by 3% per second) and is reset back to 0 1s after you actually accomplish a crit. So after a lull in battle, you can guaranteed open up your next fight with a crit, and for the duration of the fight, your critical % is raised by a little but not a gamebreaking amount. It's a nice opening burst.
The second is "Nether Tentacles", a rune tied to the "Elemental Arrow" secondary attack, which turns your elemental arrows into big, slow, wide balls of death. It's advertised as providing a leeching effect, and it does, but more importantly it's a nice wide cylinder of AOE damage that isn't stopped by enemies, and can in fact hit individual enemies more than once (some particularly large bosses can be hit three times). It's like the Ball Lightning elemental arrow, except doesn't quite have the same coverage, but more importantly, does full damage on every hit (unlike Ball Lightning which is greatly reduced) - the leech % is only like 3%, not gamebreaking, and not overly important for DH builds in Inferno.
When you combine these, what you wind up with is opening salvos that can actually (effectively) one-shot certain Champion packs in Inferno. I just got done with a little test myself, and I was amazed at how well it worked, even with my relatively modest build (~19k base DPS with a 750dps weapon and marginal gear mostly focusing on DEX). I can only imagine how well it will work with tweaked gear centering on DEX and Crit Damage increase, which exists in some pretty substantial numbers.
The key is that Nether Tentacles move slowly enough that, at a full screen away, you can fire about 7-8 of them off before the first one hits, and because, as I mentioned, crit hit % is tied to the projectile when you fire it, all of them will be guaranteed crits and because of how Nether Tentacles work, they will all hit more than once. At a modest 30-60k crit damage range with my setup, call it 45k average, and you're talking over 500k damage to every mob in the area on your opening salvo. This is more hp than a lot of champion packs have, and those that do have more than this tend to be of the slower, kiteable variety.
It also means an insta-self-gib when they happen to have "Reflects Damage", but never mind.
regards