The Dark Paladin offers an alternative path for paladins who fall from grace. A player can choose this option with your approval.
When a paladin breaks its oath, sometimes it falls into darkness and becomes a Dark Paladin. A Dark Paladin is not necessarily evil, but it has lost the light of its Sacred Oath. Dark Paladins tap into the darkness within themselves, and can even make it manifest as a nigh tangible thing. If it embraces the darkness, eventually a Dark Paladin will even exude an aura of gloom around itself that obfuscates allies and saps the morale of others. Wherever a Dark Paladin goes, darkness follows.
A paladin must be at least 3rd level to become a Dark Paladin. The paladin replaces the features specific to any Sacred Oath it might have taken with Dark Paladin features.
- from the publisher's blurb