Envy is one of the Mirror traits in the Vaas: Insanity DLC. Each level adds another gadget socket to Vaas's weapon wheel, so you can carry more throwables and tools into a run.
Vaas starts with limited room for gadgets. Every Envy level opens one more socket, up to four, so you can bring grenades, mines and healing items together.
Walk up to the Mirror in a safe house and spend Cash, the currency you earn in Vaas: Insanity. Levels unlock in order, and each one costs more than the one before.
Yes, and early. The first level costs very little, and more gadget slots help in every fight.
Greed (Vaas)
Lets you keep more currency after dying, and at the top level recover your full inventory where you died.
Pride (Vaas)
Gives replenishing Healing Syringes, then raises maximum health in five steps.
Sloth (Vaas)
Adds syringe capacity, the Camera, the Wingsuit, Parachute and Grapple, faster crouch movement and vehicles at safe areas.
Vaas' Wrath
Improves takedowns: speed boosts, reloads, small heals, front takedowns on alerted enemies and takedowns on Heavies.