Witness your closest friend die for a second time. Literally, Sasuke will awaken it when Itachi 'dies' again.
Or perhaps watching your closest friend die for a second time upon awakening EMS. Kabuto may start out strong, but Sasuke will get rinnegan and win. Or just destroy Kabuto with EMS -.-
Or perhaps watching your closest friend die for a second time upon awakening EMS. Kabuto may start out strong, but Sasuke will get rinnegan and win. Or just destroy Kabuto with EMS -.-