@Mesanna @Kyronix @Bleak
I have done a harrower a couple weeks ago as well and can verify that the thing disappeared into thin air shortly after beginning attacking it. We did not get the scrolls like Timberwolf did above. We paged a GM... did not get a response. We checked the alter to see if the gate was still up. It was not. Skulls gone.
On a different day we did Medusa, and she disappeared on us at about 3/4 life. After several minutes of standing around confused, some of us had drops appear in our backpacks.
