To answer this question we would need more specific information given the range of contexts this question has.
- The amount of demons one can fight in a game
- TV science fiction
Science fiction TV in which games may be based can lead to the same answer. For instance, in a book or TV fiction a witch may fight one demon at a time or two. As with games, TV and books are often the same in that they make the fights fair and based on skill.
From the various contexts one may "fight demons" it all comes down to skill level. If one is playing a role playing game like Dungeons and Dragons there are specific rules as to how many villain are fought at once. In these fantasy style games it is important to follow the rules as set by the games. With computer or other video games the programmer decides on the number of demons to be fought at once. Often in these games there are different skill levels such as beginner to expert that can determine how hard the game is and therefore how many demons may be fought in the game at any one time.
From the various contexts one may "fight demons" it all comes down to skill level. If one is playing a role playing game like Dungeons and Dragons there are specific rules as to how many villain are fought at once. In these fantasy style games it is important to follow the rules as set by the games. With computer or other video games the programmer decides on the number of demons to be fought at once. Often in these games there are different skill levels such as beginner to expert that can determine how hard the game is and therefore how many demons may be fought in the game at any one time.