We went into PoM the other day and saw this strange person, hailed, asked aboutt he game and we said
"I will play hide and seek with you"
this triggered an event where she went running off, stopping every now and then. When she stopped, 2 mobs popped who attacked. When killed, she would carry on after a while. This carried on with one more mob popping every time. Unfortunately we got to 5 mobs but she despawned before we killed them all.