Taking something classically offensive, like fire or lightning, and giving them a more defensive twist. For instance, burning away damage to the party, summoning creatures made out of lighning to guard the party, boosts, wards, etc. So like I said, very close to yours. But it's also up in the air cause I like to tie that stuff to the type of character I play so it fills a larger theme. Their powers reflecting their personality, current situation, and goals.