[Having followed the dispatch's directions to the apartment, Tear quickly takes in the situation presented to her: the large black creature and the seemingly normal man fighting it off him-- surprisingly, the monster looking worse for the wear, continuing its attack in spite of that.
She's not too close to the scuffle yet, the perfect distance to cast actually, so she begins to sing, a verse low and soft to cloud its mind. The spell won't kick in completely right away, but even if the creature does manage to notice her in the growing drowsiness, the distance is enough it shouldn't hope to cross it before succumbing to forced sleep]