How about having "fixed groups" where it's the same people that groups up and get the group experience in fighting. In each group their would be specialized roles, that each took care of some special aspect of the fight. The different groups doesn't have to be equally specced, but each group member should be quite aware what his buddies are capable of - how to support them and what support he can expect.

The main thing is that we get selforganized groups that can hold their own, and leave leadership to focus on the larger scale of things (strategic level), instead of having to do detailed stuuf (tactic level).

PS: I didn't read the whole post yet (it's late at night here), so someone else might have said something equal to this.

Kind regards
AllYourBase AreBelongToUs / Borne OfFire

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Dude: "My thief BS for 800 dmg! Omfg, omfg, lawl, noobzorz"
AYB (drunk): "Do people take damage from being bullshitted? WTF???"