To clarify on my thought of targeting weak spots for melee, which could apply to all combat as well. Much like kicking or bashing to interrupting a spell. As a warrior, or any melee, your character has a perception of areas of weakness on mobs. You pick a target, lock in combat, traditional EQ style, your character notices that enemy's lower area is exposed, more vulnerable to attacks. You make the decision to attack the lower by clicking the lower stance button, on your UI, you don't have to change your stance, but if you do, you'll be more effective. Much like interrupting a spell with bash or kick, or whatever, you don't have to. Your character is now making lower attacks, the mob is taking more damage, you miss less, and have a higher chance to crit. A little while goes by, the mob changes it stance to protect itself, lower is no longer exposed but now the upper is, so you change stance also. This does not normally happen in rapid succession, but it could on more difficult fights, more powerful mobs, named, and raids. There is no dancing around, there is no button smashing, combat is locked. A simple click every now and then. You are now more engaged with what is going on in the fight, you have to pay attention to what going on between your character and the mob your character is currently fighting. It is not required to win a fight but if you do your chances of winning encounters increases, same as kicking/bashing to interrupt a spell cast.