Sorry to bump an old topic, but I just ran into this same issue with the latest version of the game. I was able to get things working by doing the following:
- Check your inventory, if you have a black Wisdom Rune, it's the wrong one. Go put it in a container somewhere if you want to keep it or just drop it.
- Go to the Rune Room which is on the top-left of the area. (Go around the long hallway past where you got the spider leg. The room to the left of the merchant is the Rune Room.)
- Find the proper rune which will teleport you to an Imp, defeat him and it'll drop the proper Wisdom Rune.
Now you should be able to complete the quest properly once you re-enter the summoning room.
