After Gideon killed Sigmund, Gideon needed a partner for his plan to kill Wyatt so he used the mirror to plan with his counterpart how to distract the sisters. They made Leo and Chris cross to the other universe, and then broke the balance of both worlds as just Good Paige and Good Phoebe crossed to the other world. Then they were after Wyatt and both Paiges and Phoebe cast a spell on him that left him hurt deathly. They used the mirror to heal each other.