I had something similar to this buildhttp://us.battle.net/d3/en/calculator/witch-doctor#bZdUeR!XVZ!aZZZaa
with somewhere around 15k hp and 4-5k dps. You can probably replace jungle for something else like Pierce the veil if you dont spam haunt all the time.
stick around the center and inner center with the 4 little circles to create some space between you and diablo. Haunt and shift click spiders as you kite him. Drop a grasp for the damage and not really the slow. Even with the 80% rune, diablo wont get slowed much. When diablo catches up to you, Soul Harvest for the HP (if you're mid/low), SW out to the other side of the hole. But always be on the other side of the circle from diablo. And keep running. When he cast stuff you have a short window to spam spiders as long as you dodge whatever he's casting (i.e prisons are easy to dodge, he only cast a certain amount of prisons and you can easily move out of them and spam for a sec or 2)
More or less the same, spiders should be able to kill the shadow pretty quickly, haunt diablo and shift click move away from diablo.
Place yourself on the opposite end of the mini circles in the center, it blocks Diablo's Fire circle and the lighting ability is easily dodge. Again, grasp when he cast something, haunt and shift click move spiders around the circle.
You wont really need to aim Leaping spiders nor do you need to aim Haunt.