FALSE DAMAGE Idea
Mind Games (ultimate) For the next 5 seconds, your abilities used enemy champions cost 0 mana, deal 0 damage and instantly cooldown. However, enemy team will FALSELY SEE their health bars taking the damage and will FALSELY SEE your mana as being spent, only to have them reset once over. Cooldown: 15/10/5 seconds.
TL;DR: "did we really take that damage? should we run? should we stay?"
Hopefully this idea will inspire another or anyone! If not, please rename "True damage" because I will always wonder what "False damage" is...