[Arryn]

Originally posted by Blofeld:
Harbingers ignore scripted orders. Pity that, instead of casting orb lightings or bLasting undead with their horn as scripted they usually cast far less effective spells.

As Graeme alluded to, you need to be careful where you place the angel. The horn is ranged 23, and orb is only range 15. I have seen my own harbingers use the horn, so I know it's not a scripting bug.