Implement free grouping

Or dynamic grouping. Basically, I would love to see it happen where, if I see someone fighting a mob I can run up along side them and help them kill it, without hindering them and while gaining some benefit as well. I enjoy doing this on my own but I would like to see it happen in some kind of official way.

The main reason I bring it up is because the opening cinematic shows this kind of grouping. The adventurer finds himself in the middle of a party battling and simply joins in by fighting as well. This kind of gameplay is fun and I believe would bolster an already great community.

So you want kill-stealing?

I don't think kill stealing has to happen, just take the existing helping system where anyone can run up and help you kill a non quest mob and modify it so that, assuming your in the proper level range, you also gain some exp, no drops imo they should only go to the orig claimer.
I like the idea of ad-hoc grouping, hell mobs do it to us, why not let us do it to them in a more beneficial to everyone way.

On the exp note, a person joining this way should probably only get their base exp * mob_health_percent when they joined in the fight, so as to not have people running around seeing people fighting have a mob at 2% hit it once and get full exp.
So basically a mob that if I solo would give 300xp but I join someone else in killing it when it's at 30% I only get 300 * 30% = 90xp
And of course the level gaps would have to be followed, being a lvl 10 chasing a lvl 45 around to leech his kills would be an equally broken system.