The ring comes to her without any accompanying disaster, at first. It comes when she's on her way home from work (she hasn't been to school in weeks), following her along and giving off a distinct sense of importance, if not urgency. Karen's not an expert on alien military tech, but she knows weird stuff when she sees it, and she's pretty sure that she's not the sort of person who should be called on to field weird stuff. Like, there's her niece, her niece is pretty weird, but that doesn't mean she's someone who can stand up to an all-out weirdness free-for-all.
"Go home," she tells the ring. "Or - maybe not home, if it's far away, but you can fly places, right? You should go talk to the Justice League in DC. Or, uh, float up to them and let them do the talking, as the case may be."
The ring gives no sign that it intends to go anywhere else. She sighs and puts it in her pocket; she doesn't put it on. She can mail it to the Justice League with an attached letter in a couple days, when she has the energy to do stuff like mail letters to people.