Dark Decade is a relic created by a god in another world, it first user was called the Destroyer Of Worlds by many. However due to an incident involved the first user and the creator. Most of Dark Decade power is gone and it was passed down into the creator son who become it second user.
Dark Decade is a unique relic that exist in belt form when not used. To activate the relice, the user only need to insert the transforming card into the belt and yell "Henshin"
The most unique function in Dark Decade is the power to change into another set of power via a card. When insert the card represent a power set into the belt. The belt itself will simulated the power by analyzing data imprinted on the card. However Dark Decade cannot simulated other Symphogear power.
Dark Decade power manifested no armed gear due to it isolated origins. But relied on a wallet that can transform into a gun and a sword called Ride Booker.
Ride Booker also contain all the card that the user need to use.
A unique characteristic in Dark Decade, is the un-deniable fact that Dark Decade can be use to kill a god. Due to being a weapon made by a god and used by his son. By using an unknown method, Dark Decade can kill those with The Power Of Gods who can substitute one version of themselves for another version.