I also did : magic, attack, life then armor (I'm far from finished for armor btw :))
However, I found that going 4 (5 now) knigdoms at magic, then 4 at attack, makes you quite brittle/weak, you die easily.
If I had to redo it, I would go : All Attack OR all magic, THEN 4-5 life, then, back to Magic (or attack), then back to life.
Armor is weak : poison, true damage, bone dragon.
Yes armor gives damage to Rowane and boombot, but going magic will also give you damage, and going life, will make sure you have time to do your damage. My opinion