Battleground and Merchant Keep Take Quests
Upon successfully killing the Keep Lord/Jarl/Chieftain, every eligible player inside the keep region will be awarded approximately 25% of their level in experience for members of the realm who are not defending the keep. This experience can be earned once per level.
If the /xp off toggle is switched to block xp this reward will be blocked, so be sure you have the xp set to be gained before the lord is killed.