If you have the Syndicate dungeon mod on an event dungeon, i.e. one with a cauldron at the end, then you also get a cauldron + associated mob of enemies from the Syndicate boss when it dies. I reported this on Reddit but there seemed to be no interest, but it happened again so I took a screenshot.
No Wanderer in Tavern. Only [not] seen this once but seems unlikely it’s a random glitch, more likely the mod doesn’t work there.