Witch Doctor passive skills are a quirky lot. They basically fall into three categories- skills that improve your summons and summoning ability, skills that focus on a group of spells, and skills that don’t really fit either of the other categories. While the summon passive skills are by and large not very useful since the Zombie Dogs and Gargantuan don’t scale effectively, there are still plenty of interesting options in the other skills. In many cases, you’re best choosing only one of the skills that focus on a particular group of active skills (Fetish Syncophants, Spirit Vessel, and Rush of Essence) and building off of that with effects that tend to benefit those skills as well.
The Witch Doctor has a remarkable number of passive skills that mess with Life for a class that doesn’t focus much on healing, and there are also two skills that focus on the enhancements you can get to your health globe pickup range. Curiously, you’re unlikely to want both of those skills in the same build, but then, the Witch Doctor is a rather erratic class. Keep in mind that your Mana pool will increase much like your Life does, so while restoring mana based on a percent of your maximum is strong, not many skills are worth worrying about percentages of their mana costs individually. It’s possible to go a long way to cutting your Mana spending and boosting your Mana regeneration at the same time, and with five different skills that do it, it’s a little difficult to pick a way to focus on Mana. On the other hand, it’s completely possible to ignore those skills entirely and still not be all that bothered- you just have to pick your active skills a little more carefully to make up for the lack of improved Mana regeneration.
Circle of Life: Whenever an enemy dies within 12 yards of you, increased by effects that increase your pickup range, there is a 5% chance that a Zombie Dog will be spawned from the corpse.
If I had a dime for every skill made useless by the poor scaling of Witch Doctor summons.... Circle of Life, thanks to the poor quality of Zombie Dogs in higher difficulties, is more a novelty than anything else, particularly with the especially low chance of actually generating a Zombie Dog. If, for some reason, you’re really fond of the critters after they outlive their usefulness (and scaling), there are better ways to get ahold of them. Relying on your pickup range is also a bit strange, particularly since it’s unlikely to increase by more than four or five yards. It doesn’t hurt that if you were focusing on summons, you’d likely be staying far away from enemies whenever possible, making it that much harder to squeeze Zombie Dogs out of this skill. So, generally speaking, this skill is still going to be mostly useless (if amusingly quirky) even when Zombie Dogs are made relevant. Pity, that.