limit XP gain to level ranges

[seiyria]

if you're too high level over something you're fighting (maybe 10 levels or more higher than the other team, OR you only get XP for monsters killed that are within YourLevel-10 range), you should get no xp from that fight. Additionally, your party members should get a reduced amount of xp in this case, as well.

[calthax]

Inversely I think if you're low level enough you should get more exp for that fight

[seiyria]

Yes, that case is still open-ended to account for bonuses from beating higher level foes.