Ethereal Shade showed up in warden expedition without any runes used

Just did a normal warden expedition without using any runes. After defeating the last enemies in the first map, the Ethereal Shade appeared even though I had not used any runes at all.
I did not try to summon anything since i was solo, so I don't know if that would have worked or not.
Kevfire
Guild Leader
Neverwinter SOLO Alliance