The Shapeshifting Boon Ring - easily one of the most powerful and overlooked items in the game - provides a 1D4 Bonus to all skill checks while you are disguised (Disguise Self spell or kit or Mask of the Shapeshifter all work).
However, if you take off the ring the buff persists until long rest. As such I am able to use Mask of the Shapeshifter to give this buff to my entire party. It's already crazy OP but this is a big exploit.
