2 things I don't get

[Ewierl]

Note that shields don't help against Earthquake, since "shield parry" is a special defense modifier that always works fine against attacks, but not against spells.

For mages, you might get some mileage from Main Gauche of Parrying, but Robe of Shadows may be a better bet (the MG isn't going to help against much else).

I wouldn't worry too much about SCs; any worthwhile SC should have well-above-human HP, plus some combination of defense/regen/luck/etherealness, all of which put together should make Earthquake irrelevant.