Underworld Breach can be solved with Damping Sphere, but given that Rest in Peace also gets the job done in that match-up, it earns the full four sideboard slots
It doesn't have an impact yet on the B&R list, because at this point, Type 1 (Vintage) and Type 2 share the same list
Each of those themes will give you a separate page, and the high synergy cards will be different
As a result, rather than flashing back a Dread Return and triggering Bridge from Below, the new Dredgevine build attempted to fill the graveyard with Vengevines, cast a couple of Gravecrawlers or Skaab Ruinators in the same turn, and then return a bunch of hasty Vengevines to the battlefield and hopefully kill the opponent with a big hit of surprise damage
It is a little polar in performance to be considered a great design but it is easily one of the fairest and most balanced good counterspell cards so there is that
(Extended Art, Surge Foil) Better than everybody dying