Purely mental battles are hard to show with special effects. Sure, you can have the characters sweat, strain, or show veins swelling on their forehead. But when a character with Telepathy or other Psychic Powers pushes them to the limit, or when a character is under mental attack, nothing quite exemplifies the true state of affairs like a thin trickle of blood oozing from their nose.
Exactly how [...] [tvtropes.org]