Amplifiers allow you to customize and specialize Champions to suit your play style. They come in two kinds: Mods and Augments.
Augments increase your stats directly, improving two stats on each Augment.
You unlock Mods and Augments using Merit and also when you gain Protector Levels. Amplifiers Sets, which consist of 3 Mods and 4 Augments, can be customized at will. To use a custom Amplifier Set, select it in the lobby at the same time you are choosing your Champion and Stolen Powers.