This is exactly why I like geo. Most of its skills will be resisted by magical armor but if you find yourself surrounded by wizards with zero physical armor earthquake is the way to go.
Not sure about the warrior-earthquake combo. Warfare already grants enough cc skills that are resisted by physical damage and they will scale with Warfare and STR.
I have never had too much use for Hydro other than using Armor of Frost from scrolls or memorizing some damaging spells specifically against opponents with water weakness.
I use Aero almost exclusively for utility.
Then again, I never tried using a 4-man mage party before as the OP is suggesting. Might go for that in my next playthrough as a different type of challenge.
