For a combat situation to run smoothly and effectively, rules, orderly conduct, respect of the other players' enjoyment and character goals as well as things as trivial as the spam factor must be taken into consideration. Actions in combat situations (or even intense roleplay situations amongst large groups) need to be respect the following.

Overview
Take Turns: one action per turn
No Cutting in Line: one turn per action
Pose with Caution: pose your own actions and reactions
Respect Others: try not to intrude
Pay Attention: do not ignore others
Damage and Injuries
Stopped Time