Reflectga is an upgrade of the Time Magicks spell Reflect. In the original PlayStation 2 version, it is a Time Magick 7 license that costs 110 License Points. It can be bought in Archades for 6,800 gil and (initially) costs 24 MP to cast.
In the Zodiac versions, Reflectga is a Time Magick 9 license that costs 100 License Points. Reflectga cannot be bought, and can be obtained from a chest in The Edge of Reason area of the Feywood. It is available for the Time Battlemage and Machinist job classes, although Machinist must obtain the license for Famfrit first.