There are two ways to resist the effects of magic.
First, you can make Resistance Rolls like for any other consequence.
Second, if your character has a magical ability of 1 or more, you can use countermagic.
Anyone who is themselves a magic user can use countermagic. This is rolled like any other spell (see Casting Spells). The incoming spell's effect is then reduced by the countermagic, depending on the roll and whether or not the defending mage knows the Magic Path of the spell he is defending against:
| Countermagic Roll | known path | unknown path |
|---|---|---|
| 66+ | no effect - fully countered | two levels |
| 6 | two effect levels | one level |
| 4-5 | one effect level | nothing - full effect |
| 1-3 | nothing - full effect | nothing - full effect |
A witch is being hit by a harm spell with great effect, which would cause severe harm. She uses countermagic, but is not familiar with the harm magic path. Her roll is a full success (a 6), which means she reduces the effect by one level, from great to standard, suffering moderate harm.
It is possible to resist first with countermagic and then reduce the remaining consequences further with a resistance roll.
Note that the defending mage can use all the options of Casting Spells to improve his countermagic roll, though using a ritual will commonly be impossible given the time required. But he can spend stress or mana.
Note also that countermagic is subject to Casting Spells > Mana Burnout, just like any other use of magic. Failing a countermagic roll not only means you suffer the full blast of the incoming spell, you also mark mana burnout.