A dramatic personality change. The character's personality changes radically, so that alignment is affected. Consider the five alignments a line, running Law-Good-Neutral-Evil-Chaos. Roll a D6:

1-3 Alignment moves one step towards Law
4-6 Alignment moves one step towards Chaos

Not that Lawful characters can only move towards Chaos and vice-versa. The GM should make sure that the player keeps to the new personality of the character, docking experience points if necessary.

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