I was at the bottom of Gonarch's Pit shooting at her when a hole opened up next to me and the web holding Gonarch collapsed, so she landed on the same level as me. I jumped into the pit but not into the teleporter (I landed on one of the ledges next to it), and Gonarch followed me in and landed on the teleporter. I then jumped onto the teleporter, arrived in Interloper, and Gonarch was standing right next to me! She hit me and I fell off the rock we were on.

The rock she was standing on collapsed and I ended up luring Gonarch through one of the instant-death holes and she disappeared.