You will find different discount packs for the different functions of the game such as permanent skins, partners, cards to advance a character you already have. Each pack is composed of the object and gold.
The Red or Gold Evolution Cards:
These universal cards are essentially used to advance, power-up your partners you already have but of red or gold quality without having the card.
When you want to increase the stars in the Akatsuki function, from the Red Quality, you can use two options: character fragments or Universal Card.
Permanent Skins are transformations that bring extra bonuses to your team.
Note that some of them have a limited duration (2 days). You can check that by clicking on the card before you buy it.