Effects of Changing Alignment (DMG)

Although player characters can change alignment, it is not something that should be approached lightly, since there are serious consequences. When a character changes alignment, he does more than just change his attitudes. He is altering his perception of the world and his relationship to it. Much of what he learned previously was flavored by his alignment. When the philosophical foundations of his life change, the character discovers that he must relearn things he thought he knew.
There are two possible effects of changing alignment, depending on the situation and circumstances of the change. The first results in no penalty. This effect only should be used when the player and the DM mutually agree that the character's alignment should be changed to improve the play of the game.
Most often this occurs with low-level characters. The player character's alignment may prove to be incompatible with the rest of the party. A player character may simply be more interesting for everyone if his alignment were different. Inexperienced players may select an alignment without fully understanding its ramifications. Discovering they simply do not like the alignment, they may ask to change. Such changes must be made with mutual agreement. As DM, try to accommodate the desires of your players.
In the second type of voluntary change, the case cannot be made that the alignment change would be for the good of the game. This generally involves more established characters who have been played according to one alignment for some time. Here, the effects of alignment change are severe and noticeable.
The instant a character voluntarily changes alignment, the experience point cost to gain the next level (or levels in the case of multi-class characters) is doubled. To determine the number of experience points needed to gain the next level (and only the next level), double the number of experience points listed on the appropriate Experience Levels table.
:For example, Delsenora the mage began the game neutral good. However, as she adventured, she regularly supported the downtrodden and the oppressed, fighting for their rights and their place in society. About the time she reached 5th level, it was clear to the DM that Delsenora was behaving more as a lawful good character and he enforced an alignment change. Normally, a mage needs 40,000 experience points—20,000 points beyond 5th level—to reach 6th level. Delsenora must earn 40,000 additional experience points, instead of the normal 20,000. Every two experience points counts as one toward advancement.
:Delsenora started the adventure with 20,000 experience points. At its conclusion, the DM awarded her 5,300 points, bringing her total to 25,300. Instead of needing just 14,700 points to reach the next level, she now needs 34,700 because of her alignment change!
If an alignment change is involuntary, the doubled experience penalty is not enforced. Instead, the character earns no experience whatever until his former alignment is regained. This assumes, of course, that the character wants to regain his former alignment.
If the character decides that the new alignment isn't so bad after all, he begins earning experience again, but the doubling penalty goes into effect. The player does not have to announce this decision. If the DM feels the character has resigned himself to the situation, that is sufficient.
:For example, Beornhelm the Ranger carelessly dons a helm of alignment change and switches to chaotic evil alignment—something he didn't want to do! Exerting its influence over him, the helm compels Beornhelm to commit all manner of destructive acts. Although unable to resist, Beornhelm keeps looking for an opportunity to escape the accursed helm. Finally, after several misadventures, he cleverly manages to trick an evil mage into removing the helm, at which point he is restored to his previous alignment.
:He gains no experience from the time he dons the helm to the time he removes it (though the DM may grant a small award if Beornhelm's plan was particularly ingenious). If Beornhelm had chosen not to trick the mage but to work with him, the change would immediately be considered a player choice. From that point on Beornhelm would earn experience, but he would have to earn twice as much to reach the next experience level.
A character can change alignment any number of times. If more than one change occurs per level, however, the severity of the penalty increases. (The character is obviously suffering from severe mental confusion, akin to a modern-day personality crisis.) When a character makes a second or subsequent alignment change at a given level, all experience points earned toward the next level are immediately lost. The character must still earn double the normal experience.
:Delsenora drifted into lawful good. Now she finds lawful good too restrictive. She is confused. She doesn't know what she believes in. Her head hurts. The character reverts to her earlier neutral good habits. Bedeviled by indecision, she loses the 5,300 experience points she had already gained and now has to earn 40,000 to achieve 6th level!