The 13% (I think) spell damage curse would be strong.
The ranged AoE stun has strong potential for bursting someone down.

Fear or Death Coil (my Warlocks /say Skill Coil, whenever I press DC), can be used for a short Crowd Control or Interrupt effect.

Nether Protection can really help vs casters.

Soul Link with most likely a Fel Puppy, makes them much less squishy.

They have decent burst, which is nice.