Emma defeats Gideon with light magic.

Light Magic is a type of magic featured on ABC's Once Upon a Time. It is one of the most powerful types of magic, able to overcome dark magic and render practitioners of darkness defenseless. Generally, only Saviors can use light magic, although there have been exceptions with other magic users. The one common denominator with light magic seems to be the fact that all instances in which it is used come from acts or feelings of true love.