a boon or a bane

Something that is either good or bad. All this work is either a boon or a bane—we'll find out which when we see if the workers can keep up with it all. All these toys from my parents will prove to be a boon or a bane depending on how much the kids fight over them. Running is usually a boon or a bane for me—I love the endorphins, but I sometimes really feel my old knee injury the next day.