A thrall went down beside a rampart. I went to mercy kill it, but simultaneously mounted the rampart. While the thrall did die, I was stuck in the rampart. The only key I could press was Esc. No abilities, no shooting, no aiming, no chat, nothing. The rampart UI wasn't fully visible. My warframe also seemed to be clipping into my camera, doing idle animations. This is the same mission I killed my lich. I was afraid I wouldn't get the weapon or recovered items. Luckily, I was able to contact a friend over Discord and invite them into the mission. This caused an enemy to find and kill me. Reviving fixed my predicament.