Spell defense

When a hostile spell (magic or prayer) hits you, the game rolls your spell defense. A successful spell defense check usually reduces the effect or ignores it entirely. Your chance to resist depends mostly on how the caster's level stands against yours, on your spell defense and on other factors.

Levels. The higher the caster's spell is above you, the worse your odds, and the lower it is, the better. The caster's spell level counts, not just the real level.

Spell defense. Spell defense from items and spells adds on top, and the returns diminish: the first points help most. A caster far above you cuts through all of it.

Shifts. Resistance to the spell's damage type helps you, vulnerability hurts. Resistance to spells (spell resistance, some races) works for every spell and prayer, resistance to magic only against magic and resistance to prayers only against prayers. Berserk helps too, while a good caster's holy craft against evil works the other way. Curses that worsen your spell defense, like curse or anathema, set you back.

However much you stack, you are never fully safe and never fully doomed, unless you are immune.

Deadly spells. Power word kill, disintegrate, witch curse, sleep, paralysis, narcotic mist and banishment: a successful spell defense check always protects you. A failed one is not automatically fatal.

Dispel. Cancellation and dispel affects depend on the level of the spell against yours, and are never certain either way. Your own curses on a foe are harder to lift with your own dispel.

Score shows your chance to resist a caster of your level and how much damage your armor stops. Identify, lore and affects show what an item or an effect does to that chance for you, at your level and with what you already wear. The same bonus is worth more to a fresh character than to one who already resists most spells.