Casting an evil spell is an evil act, but for most characters simply casting such a spell once isn’t enough to change her alignment ; this only occurs if the spell is used for a truly abhorrent act, or if the caster established a pattern of casting evil spells over a long period. A wizard who uses animate dead to create guardians for defenseless people won’t turn evil , but he will if he does it over and over again. The GM decides whether the character’s alignment changes, but typically casting two evil spells is enough to turn a good creature nongood, and three or more evils spells move the caster from nongood to evil. The greater the amount of time between castings, the less likely alignment will change. Some spells require sacrificing a sentient creature, a major evil act that makes the caster evil in almost every circumstance.