Troops vs magic, what am I doing wrong?

[krpeters]

OK, so I found a convoluted way of getting some serious firepower at seriously low cost with magic. Is this sort of result typical, or am I taking advantage of an exploit that's likely to get nerfed?

1) EA Ermor
2) Principe meat shield
3) 5 Augurs. No, not Auger Eldurs (250 Au apiece, expensive! 80 Au Augers -- cheap!)
4) 3 astral pearls on the 5th Augur.

Lead Augurs are scripted to Communion Slave, Hold, Hold, Astral Fires, Astral Fires.

Tail Augur is scripted to cast Communion Master, Power of the Spheres, Light of the Northern Star, Astral Fires, Astral Fires.

Cost: 400 Au, 3 pearls
Result: 10x Astral Fires.
Efficiency: Medium. If an Astral Fires does 50hp damage average (depends on if I'm up against good MR troops or not), then it works out about even.

Smashing the AI with a pile of Principes is a whole lot easier, though