Mag/Prime

"Frost Prime has the same chilling abilities as Frost but its altered mod polarties offer different possibilities for customization. It is also rumored that this Warframe has a unique reaction to certain Orokin technology."

- In-game description

Frost Prime is a Primed Mag, featuring an additional ? polarity slot, but otherwise identical. The blueprint for Mag Prime is attainable from ? along with it's components.