You could avoid double clicking to attack a monster ?
why not just a click : if the ray collision hit a monster than your character
would attack it,
and if you would click elsewhere your character would go to the clicked place.

And why not , a let your character continue fighting automatically once you have
clicked on a monster.

Another idea for later :
You could also copy some mmorpg interfaces and have menu icons for special powers that would replenish as time pass