Target creature you control gets +2/+2 if it's a host or has augment. Then it fights target creature you don't control.
You must be able to target a creature you control and a creature you donâ€™t control to cast Really Epic Punch. Note that you can target any creature you control, even if it isnâ€™t a host or doesnâ€™t have augment. It wonâ€™t get +2/+2, but it will still fight.
The +2/+2 is permanent. It doesnâ€™t wear off as the turn ends.
A combined host/augment creature will get +2/+2 because it has augment.