Does an NPC reduce the XP? I checked a couple builds ago and if a party member is involved in the combat, everyone (that isn't dead) gets experience even if NPCs do all of the damage to kill an opponent. I didn't specifically check XP with and without NPCs involved, though.
The way it used to work is that XP was awarded to whoever got the killing blow. If an NPC got the killing blow, no XP was earned from the MOB (even if you did most of the damage).
Then (at our request) they changed it so that MOBs awarded reduced XP if NPCs contributed to their death.
It's been quite a while since that change, and they may have changed it again to award full XP regardless of participation. I know during the first orc fight on the beach I receive XP when the guards kill an orc completely by themselves. I'm just not sure if it's still "reduced XP" or full.
