Explosive Growth is worth trying with any Ritualist/Necromancer MM-style build. Coupled with Bone Minions, it triggers twice everytime you summon another set.

Boon of Creation also does the same. Explosive Growth is Spawning Power, so to get the full effect you'd have to be a Ritualist primary.

I was testing it, just fooling around with:

1. Boon of Creation
2. Explosive Growth
3. Animate Bone Minions
4. Death Nova
5. Taste of Death
6. Pain
7. Bloodsong
8. Flesh of my Flesh

I haven't fleshed it out, I was mostly just seeing how effective it could be. I was encouraged by the initial results. As you can see, I don't list attribute allocation, I'm not sure of the best setup for that. I'm not completely sold on having Spirits a part of this either.