If you have 50 Resisting Spells and you're facing off against someone with 100 Magery casting Explosion, you will have ~10% chance to resist. You can completely resist certain spells such as Mana Vampire or Poison.
It is vital in most, if not all Player vs Player, templates. The Resisting Spells skill simply grants a passive chance to reduce or prevent damage of offensive spells cast on your character.
