[starslayer]

I don't like Gold & appel's answer because it makes having:

DR 1 Malediction proof, reflection == full power malediction hit the caster.

I would instead go with one of the following scenarios:
In both cases DR reduces margin of success, and if it reduces MOS below 0 then the malediction did not have any effect.

1- A malediction with skill = reflected damage hits the caster (so if mDR was 5, then max skill of a reflected attack is 5; note this has the interesting scenario where potentially both parties could be affected by an affliction)

2- ONLY if the mDR stops the attack (before the resistance roll) it is reflected with full force against the attacker. IE- Witch will skill 18 rolls a 15 (MOS 3) and hits someone with mDR 5 (making it a failure before resistance is even rolled)- witch now attacks self with malediction. If witch had rolled a 12 or below then the victim would just have gotten a +5 on there resistance roll.