The Necromancer can with Sceptre and Dagger stack up quite a lot of conditions for a huge amount of damage, particularly AoE.
You can pull with the sceptre (1) and then drop Grasping Dead (2) and Enfeebling Blood (5), then Corrosive poison cloud (7) & Blood is power (8), followed quickly by Deathly Swarm, as 7 & 8 put conditions on yourself. Now your target has many conditions on it. Epidemic spreads them to all nearby mobs.
If you are lucky/quick, you can get epidemic off before the first mob dies. Then you just DS and hit Life Transfer and lol as everything around you dies.
Taking curse and spite traits is best for this.