I had it in only 1 game - in my game with paladin on impossible. I forgot to post the build, but it was there. I never found much use of it... You get only a few runes, that will either make or don't make the difference.
As for the crystals, the fighter classes will find little use of them, as their troops are the ones that actually do the fighting, and the best the warrior or a paladin can do is to buff. As for mages, alchemy is more than enough in my opinion.
In any case, I do agree that the skill has its uses.
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