20 my game is tripping
You have Poppy in your team, that’s why. She and Helo have a chance to summon that kind of stones when they fire.
Ah ok, thank you for the prompt reply
Now I’m hoping that those underwild stones can overwrite oni curses!!!
Probably not, but one can always dream 
That would the best update ever, dealing with those oni stones are so stressful!
No, the underworld stones can only spawn on regular tiles