If Madara had still been a mortal man, Guy would’ve killed him outright. For a brief moment, Guy transcends humanity and becomes a true God Slayer. Kakashi received the Sharingan in his left eye ...

Using the power of the Ten-Tails Juubi, extremely powerful wielders like Madara and Kaguya can open the third eye on their forehead to combine the power of the Rinnegan and the Sharingan.