If your own toon and the killer is equal to or lower level than the mob you get max xp.
If either the killer or your toon are higher level than the mob you get reduced xp.
If the killer is higher level than the mob all in group gets reduced xp.
I hope that is clear
Playing since Christmas 2011
Remove BoE
Make new endgame content providing similar rewards but without the need for dominant clans
Add horizontal content