BvB
From Starsonata Wiki
BvB is the abbreviation of "Base vs. Base". It often refers to when bases are built within the same galaxy by opposing teams. In order to destroy enemy bases, players may use their own team's bases to aid them in the destruction of the opposing base. Note that the normal Player vs. Player level restrictions apply to BvB as well.
A team score of 50 or more is required to BvB for the attacking team.