http://www.youtube.com/watch?v=31VpcWV2R9E&NR=1&feature=fvwp

1:22. The Witch Doctor spits out a long stream of something at the fallen and he is engulfed in a light and then dies. Fortunately, or perhaps unfortunately, I got to use the Haunt skill at Blizzcon 09 and can recognize it. And maybe now some of my followers will understand what I mean when I say it looks awful. For those that don't want to look it up, the Haunt skill summons an invisible spirit that latches onto an enemy and does damage over time until it dies, whereby it will seek out another. The description said the spirit lasted 6 seconds, but lasted longer when possessing someone.

Now that I think about it, It's just a weaker and single-target version of Locust Swarm.

Haunt. yes.

It's essentially a fire and forget DoT that jumps around once it kills something. Pretty useful to always have out there hurting dudes.

Why does it look awful, specifically?

Julian, notorious masochist, continues to read the forums and fansites and provide more information on skills and effects.

Re: haunt, he wanted to pass along that the effect seen for the skill was "the most ridiculously temporary graphic ever." It was never really intended to be shown in the state it was, so it's all a bit embarrassing. But never fear as the skill itself is seeing an overhaul (technically and visually) to better deliver the concept of being haunted.