[llamabeast]

Oh yeah, just try Falling Fires with Marignon/Abysia, Thunderstrike with Caelum or Raise Skeletons with EA/LA C'tis and you'll see gemless combat magic can be pretty brutal.

I'd say most combat spells are gemless really. You generally just want at most a few key gem-using spells, even for big battles. Of course in emergencies it's certainly possible to use more gems with some benefit, e.g. for Shadow Blast.