Hex Machina

Bad Ex Machina.

The negative version of Ex Machina, like what the slidetext said. Instead of helping characters with the abrupt appearance of something or someone to the scene, it prevents these characters from completing a very crucial task to the story, such as knowing how to get out of a labyrinth or what magical concoction would kill a monster that's hunting them down. A common instance of this UnTrash playing is when someone is reading a passage (usually important instructions) aloud, then as they reach the word "is", "are", or "by" of said passage, they get cut off by a Hex Machina, keeping them from continuing reading their instructions. It's now up to this person to Figure It Out alone at a later time.