I love love love Zombie Charger - Undeath so I decided to make a build with it as the focus.
This build has no escape ability so that may need to change... we'll see how it works in practice.
The goal is to have a bunch of targeted damage that weakens a single monster and then to use Zombie Charger - Undeath to full effect. Also note... while I focus on the main target, the rest of the monsters should be slowly ticking away due to Locust Swarm. When I start the chain reaction it should continue fairly easily due to this.
1.) Passive AoEs - Zombie Dogs and Garg will passively be weakening everything.
2.) Start off the fight with a single cast of Locust Swarm
3.) Haunt + Spirit Barrage on the main target until the target gets low.
4.) Cast Zombie Charger to kill everything all at once. Hopefully they'll be low enough from Locust Swarm to make it fairly easy to cause a chain reaction. Most everything should die after a few casts of charger.
Gruesome Feast passive can be changed to bad medicine if the pets can't stay alive enough.
It sounds like a lot of fun to play although it will take skill to make sure zombie charger gets the finishing blow and not the dots.
I'm a big fan of Soul Harvest but I decided against it for this build. There isn't a single ability I'd feel good about dropping for it. The combo gets weaker without Haunt + spirit barrage + locust swarm + zombie charger and I need the summons to help me stay alive.
Yeah, I had darts in there first but I decided that spirit barrage is only 50 more mana with that rune. I think that early level, you'd have to use darts instead because the mana glyph from haunt isn't until near max level. It's kinda cool that it only requires level 30 if you switch the haunt rune though.
Flash Fire actually homes... I've seen it on the spotlight video... What would be good to test is if the first hit hits no target, will it bounce to a close one ? If the answer is yes, you could spam it from afar hoping it will bounce to the boss while you're taking some breath