Only immunity will provide this. Scrolls may occasionally have no effect when read. Damage of monster spells and melee attacks is doubled. Monsters never miss in melee and spells never fail. Monsters get critical hits in melee more often.
Players get critical hits less often.
Ball spells initiated by the player will damage the player if he is in their sphere of effect. Selection of shopkeepers is biased towards those with the lowest purses. Shopkeepers never rotate. Shopkeeper greed is increased by 20. Shops are less likely to stock piles of an item and piles will be smaller.