A 3:1 brew-restore ratio is generaly the best. You can't finish where you left off during the fight, just during the actual quest, I.E. you can't hurt the Queen to half, leave, and then finish her off. You probably will run out of special attack bar towards the end, there's no way to get it back up besides the potion, basically leaving you helpless to her special. (Special attack restore pot) You can't help your melee soldiers if the Queen manages to get her spec off, and you can't save yourself from it, as far as I know. Also, make sure you kill the Defilers. (Maybe Ravagers? I can't remember, the purple ranging ones) They target your archers, which are imperitive. (They hurt the healers)