SECOND FILTER. (tw: horror and gore)
You play D&D, you know what a Mind Flayer is. They called this creature that had Will in the Upside Down for a while the Mind Flayer, and he sort of somehow came through and possessed Billy, and then Billy went around getting other people possessed. That's what actually happened at the mall. This giant meat spider was trying to kill Eleven and grow bigger and just — it was made of melted people. Like they just stopped being human and turned into meat and the Mind Flayer controlled it.