Actually, I think I use axe, not dagger.
Warhorn. It's like this:
Pull a group with Axe/Warhorn equipped.
While they're running in hit them with Wail of Doom.
Attack foe in the middle of the group with auto attack.
Use Unholy Feast and Locust Swarm.
Swap to staff staff, slam down all marks.
My necro is a baby still, so who knows how effective that will be at higher levels, but Warhorn, Axe, and Staff together are some good AOE damage.