No, that isn't even close to the correct way to script what you are wanting.  It sounds like you are wanting to reset a bosses HPs when everyone in the zone does, or after aggro has been cleared due to a failure to kill the boss.
You will want to refer to the quest wiki pages here:
http://www.eqemulator.net/wiki/wikka...=QuestTutorial
and here:
http://www.eqemulator.net/wiki/wikka...a=QuestObjects
This should do what you are wanting:
	Code:
	sub EVENT_COMBAT {
	if ($combat_state == 0)
	{
		quest::sethp(100);
	}
}