That is an Impale DH, lot's of fun if you want to kill mainly elites.
The build generates hatred through the use of it's weapon which has the unique property of returning 15 hatred for every enemy you impale that you have already impaled. Through clever use of a couple of different runes on the skill impale, you will hit multiple targets with every shot of impale - provided there are enough enemies around you - and you will generate more hatred than the cost of each impale.
I've used this build quite a bit and it's a tough build and the main build I use for HC - but - you have to keep the various defensive buffs active otherwise, you will die suddenly. Best at Greater Rifting. You hit one enemy with 75,000% weapon damage every time you throw impale, so you can kill anything fast, but one at a time. It is meant to be played as a vault to elite, kill him, vault to next elite, kill him, etc. Very fast play style. It becomes so powerful it doesn't work well in T13 because you one shot everything and you don't get to impale enough things a second time to continue generating hatred.
I also use the Multi shot UE set for HC and it's fun, allows you to stay way back from danger and you can proceed cautiously killing everything from range. Pretty tough build, easy to play and you kill sreenfuls of enemies at a time. Very fun and best for Torment level farming.
At the beginning of this season I used the Nats/Marauder 6/4 piece combo and the main damage dealers are the Sentries so you again get to stay back away from danger and have the added bonus of having all pets at all times. The pets not only tank and give a number of passive benefits, but they also give a range of active solid benefits on a 30 sec cooldown timer. Super effective skill for this build. I came away from it with the idea it might be the best DH HC build. I'm playing SC atm, but when I return to HC, I will definitely try one of these. It's a little more work than the UE Multishot, but if you're young and looking to be active you'll like it.
Edited for speling adn grmmer