Mal als Referenz, der komplette Abschnitt aus dem AD&D 2nd PHB in seiner ganzen Arschigkeit:
The paladin is a noble and heroic warrior, the symbol of all that is right and true in the
world. As such, he has high ideals that he must maintain at all times. Throughout legend
and history there are many heroes who could be called paladins: Roland and the 12 Peers
of Charlemagne, Sir Lancelot, Sir Gawain, and Sir Galahad are all examples of the class.
However, many brave and heroic soldiers have tried and failed to live up to the ideals of
the paladin. It is not an easy task!
Only a human may become a paladin. He must have minimum ability scores of
Strength 12, Constitution 9, Wisdom 13, and Charisma 17. Strength and Charisma are the
prime requisites of the paladin. A paladin must be lawful good in alignment and must
always remain lawful good. A paladin who changes alignment, either deliberately or
inadvertently [sic], loses all his special powers -- sometimes only temporarily and sometimes
forever. He can use any weapon and wear any type of armor.
A paladin who has Strength and Charisma scores of 16 or more gains a 10% bonus to
the experience points he earns.
Lawfulness and good deeds are the meat and drink of a paladin. If a paladin ever
knowingly performs a chaotic act, he must seek a high-level (7th or more) cleric of lawful
good alignment, confess his sin, and do penance as prescribed by the cleric. If a paladin
should ever knowingly and willingly perform an evil act, he loses the status of
paladinhood immediately and irrevocably. All benefits are then lost and no deed or magic
can restore the character to paladinhood: He is ever after a fighter. The character's level
remains unchanged when this occurs and experience points are adjusted accordingly.
Thereafter the character is bound by the rules for fighters. He does not gain the benefits
of weapon specialization (if this is used) since he did not select this for his character at
the start.
If the paladin commits an evil act while enchanted or controlled by magic, he loses his
paladin status until he can atone for the deed. This loss of status means the character loses
all his special abilities and essentially functions as a fighter (without weapon
specialization) of the same level. Regaining his status undoubtedly requires completion of
some dangerous quest or important mission to once again prove his worth and assuage his
own guilt. He gains no experience prior to or during the course of this mission, and
regains his standing as a paladin only upon completing the quest.
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Man beachte, dass diese Regeln einen völlig mit der Frage alleine lassen, _was_ denn jetzt eine Böse Tat wäre.