A lot, yes. The people here call it "Corruption". Aside from general arm pain, it's caused a great deal of headaches, too, and sometimes I hear the entity's voice in my head. Again, it's a solvable issue, but I'm trying to study it more concretely...

All of this is to say, don't touch the black plants in the forest. I'd hate to see someone else fall to this. Mine was intentional, and I'm happy to confirm it sucks.

[Thanks, Thorns.]