Shattered Kingdoms

Okay just for clarification here, is it alright for a light aura PC to train on grey aura npcs?

I personally think that dark vs all auras = ok. Grey vs all auras = ok and light could kill both dark and grey, but never light. Is this correct?

I don't know why you would level on grey NPCs. There's darkie NPCs for every leg of the journey and the xp bonus for leveling on them is going to be far better than leveling on some grey NPCs.

True, its not very efficient but I was more curious if its considered breaking alignment.

I assume we are talking about intelligent humanoids here not animals. If by train you mean kill, then the commonsense answer is 'no'. If by train you mean stun then maybe, but you should still have a good reason why you would go around indiscriminately bludgeoning people into unconsciousness.

It's not just lighties that should take care. Killing random people for profit implies miscreant alignment or worse. Any character with a less evil alignment ought to have a better IC reason. How good that reason has to be depends on the alignment.

IMO, grey-aura characters have as much trouble here as principled characters. But lighties killing NPC lighties is a more clear-cut conflict, so it's more likely to get cursed.