Nephilim Bolt Thrower

The Bolt Thrower is a solid beast. At six points it's at the high end for what you pay for a light, but is solid enough in its specialised role of denting large targets and picking off solos and officers that it still sees play . If I'm running beast light I'll often throw one in as extra fury and to keep my opponent honest at range. I don't ever take two except with Epic Lylyth, and even then that will probably change once the Naga comes out.

Nephilim Protector

The Nephilim Protector is a rather limited model. It has no ranged ability and is also pretty blah in melee with MAT 5 and POW 12. It's job is to take it to the face, either with Shield Guard or blocking charge lanes. And on the occasional time you run into deadicated knockdown his animus can protect you.

The only warlock I have found that I'm willing to take it regularly with is pThagrosh. Because of Fog of War and Death Shroud, once you put Tenacity or Spiny Growth on the Protector it can actually stand up to enemy damage. At ARM 20 (with Spiny Growth) at range he can take a few big hits, and at DEF 15 ARM 21 against charges (Set Defense + Tenacity + Death Shroud) he can actually get in the way and block the charge lane to a heavy without dying.