Was on another site, and we talked about what would be appropriate penalties for teamkilling - as the devs have said in twitter that team killing will be in but penalized. How about the following:

Loyalists: Decreased requisition point gain for a while. Decreased money
Do it a lot? Realigned to Chaos.

Chaos: Khorne smiles upon you.

Orks: No penalty, other orks give teef.

Eldar: Requisition point gain decreased for a while. Slaanesh smiles upon you.

And in all cases, team killing you shouldn't yield a penalty for a while after you team kill.

I don't mean to de-rail the thread but as for Chaos there should be an option for duel's that would result in some sort of reward regarding Khorne. Like for honorably destroying your opponent you gain a buff (perhaps?) that gives you like 10% more item find or something.

I AGREE BLOOD FOR THE BLOOD GOD!

but as in reguards to dueling for the other gods I wouldn't know it would work tzeentch maybe takes a relic from you nergal just makes your body decay slaanesh.... I don't wanna think about it.

The main problem I can see with your suggestion is that if a Space Marines goes to Chaos he literally can't go back.

I don't see the problem.

If you accidentally team kill you're force faction swapped?

i think it would be cool if war masters or captains could challenge a chaos champion or a ork warboss in single combat and who ever wins, they give everyone a moral boost or a bonus increase to damage.

Note "Do it a lot". The threshold for this should be high enough that it doesn't happen by accident.

Space Marine: The Inquisition is watching (5% reduction in damage and health that stacks the more you do it)
Chaos: Pain and Servitude (5% damage increase but 10% health reduction)
I don't know about the others and I'm really just throwing stuff out there on this one.

What like a thousand kills?