When around mobs at night on game, mobs all of a sudden freeze - in place, while still making the sound that the mobs makes, get close to that mob, and an invisible same mob of that same kinds chases after you and attacks, trying to attract the invisible mob does no harm to it, attack the part of the mob that froze then attacks that mob. The mobs aren't supposed to freeze, or in mid air so that an invisible mob of that same kind may attack the user and attacking the invisible mob does no harm to it, of having to attack the part of the mob that froze then does damage, tho the frozen part of that mob does drop the items they are supposed drop, the mob are supposed to take damage and not freeze,  so that an invisible same mob can attack user with no attacks taken from the user.