Troops vs magic, what am I doing wrong?

[krpeters]

OK, this has been bugging me for a while, and I can't seem to figure out what I'm doing wrong.

I typically play SP against several Difficult AI opponents. No matter what I do, it seems like troop strength seems to matter way more than magic, at least up to level-6 research. At what research level is magic really relevant?

For example, I was recently trying EA C'tis. I thought a good easy strategy to use magic would be to hand a few Reborn some death gems and let them cast Shadow Blast. But when I do the math, it doesn't add up:

Reborn: 100 gold
Death gem: equivalent to 25 gold
Shadow Blast: hits 7 squares, I estimate smacks a net 15 gold worth of enemy troops per square (between misses, hitting my troops, and similar effects)
7 * 15 = 105, < 125 gold.

For 125 gold I can field 9 Elite Warriors which are going to do a lot more damage.

Only other thing I can see to do is hand the Reborn three gems, to get a fatigue reduction on the first casting so they can cast it a second time. But that's equivalent to 175gold cost, which is still not that efficient against 210 damage.

Seems like I should skip recruiting mages altogether, take the extra cash and build castles, and just build a swarm of Elite Warriors. I've tried this, and it works really well. What am I missing in my attempts to use magic effectively?

Karl