How do I get to the Forgotten Cell without playing Hide-and-Seek?

Solution 1:

There are a few ways you can discover Withermoore's cell:

You can try talking to Moby with a new character, that should give you a fresh start at interacting with him. Note, however, that not all NPC dialogues reset when talking as a different character, and I'm not sure if Moby is one of them.

If you have a dwarf in your party, they can enter the small hole without any troubles, and uncover the hatch that's hiding the ladder from the inner side.

10 Wits just means the base level, it's not enough to discover most secrets. I believe for this mound you need somewhere around 14 Wits. Failing that, you can go over the spot where the mound is supposed to be, and simply use a shovel. Even if you can't see anything hidden, digging in that spot will reveal the hatch that leads down to Withermoore.