Double Vault is a legendary major card out of the New mechanic pool. Vault gains a second charge; each vault is 0.2 s and the cooldown 10% longer.

You can take it once · it only turns up when your Dash ability can actually use it · it can be offered for 0 of the 34 abilities.

Only one card can reshape that ability this way — this one, or Skyfall and High Vault. Take one and the rest are gone for the run.