[Void Sabotage Bug: Venkra Is Immortal]

Same here too. First time playing this particular Tower 1 mission too.Went through the portal after the key.

Wasn't expecting a mini boss encounter, but fought them anyway. Killed off the grey one pretty quickly, but the red/black one didn't seem to lose any health.

I ended up going into a room, which showed the symbol of a control console according to the map. For some reason, there were no clickable events. That boss followed me in there, again I tried to defeat her, but her HP did not budge.

Finally, I left the room to sped away to the other end of the map, only this time she didn't follow. Next thing I heard was Lotus telling me to pick up the key, and the boss had vanished. Spent a further 30 minutes clearing mobs, and looking for this key, but to no avail. I ended up having ot abort mission :(