It seems unlikely that the cultists haven't made a pact with one of the old gods, based on what we know. I fail to see how they could have done all of this without divine intervention of some sort.

[ Which means yes, it's an adjacent deity. Thancred takes a moment to follow that train of thought, his boot idly tapping against the ground. ]

It may be less about the mushrooms and more about the decay. How much do you know of the old gods?

[ In Thancred's case, it isn't much. He'd scoured Thorne's libraries and bookshops alongside Kyle and the information was scarce. Now that they're here in Solvunn, though, it might be a different story. ]