Before 7E, we used to manage magical resistance like this:
Boris the Bad sees Fang the Delectable taking the ruby ring from the tomb of the Undead Embryo. Boris wants the ruby as he needs cash for some new spells now that he's Level 2 so he whacks out a TTYF at Fang. He has INT of 22 so it looks bad for Fang. Boris makes a SR on WIZ. His WIZ is 15 and he rolls 2,5 - a L1 SR.
Fang has WIZ 9. He gets a shiver down his spine and turns to see Boros twitching his fingers and pointing. Without a thought, let alone an action, the Delectable One's own WIZ kicks to resist. He rolls them dice: 5,6. Fang too makesa L1 and Boris' spell fizzes out damply in his hand. Fang draws his gladius and pushes Boris over. He sits on the sorry son of a sorceress and chops his fingers off. 'Shan't have to worry about you now' Fang declares happily.
Boris is in great pain and goes for his new spell, Poor Baby. Uh oh! Won't work! No fingers, no dexterity. Chickens and eggs come to Boris' mind as he picks up his fingers, counts them (mentally) and slinks off back to town to find someone to do something about his digitary nightmare.