Let's go for something more like this?
Shutdown: Using his Possession technique, Juno can invade the minds of weaker enemies and effectively slow down all brain function temporarily, rendering them unable to think clearly for a period of time and to a level that corresponds to their power level. For especially weak enemies, this can cause them to fall unconscious. For enemies on a more level playing field with Juno, this can cause them to be fatigued for a short period of time. If tried on a person stronger than Juno, it would most likely recoil and injure Juno, leaving him uncapable to access his abilities for a short period of time. This ability requires Juno to make direct contact with a person's forehead, and therefore leaves him open to attack while attempting to make such contact.
EDIT: Added another aspect, italicized.
Shutdown: Using his Possession technique, Juno can invade the minds of weaker enemies and effectively slow down all brain function temporarily, rendering them unable to think clearly for a period of time and to a level that corresponds to their power level. For especially weak enemies, this can cause them to fall unconscious. For enemies on a more level playing field with Juno, this can cause them to be fatigued for a short period of time. If tried on a person stronger than Juno, it would most likely recoil and injure Juno, leaving him uncapable to access his abilities for a short period of time. This ability requires Juno to make direct contact with a person's forehead, and therefore leaves him open to attack while attempting to make such contact.
EDIT: Added another aspect, italicized.

