BvB
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. If one of the teams own the galaxy, any teams who attempt to attack it with their own bases will be required to own an adjacent galaxy for at least 24 hours. If the team you want to attack neighbors an existing team outpost or your team HQ area, provided you've owned that galaxy for 24 hours already, you can immediately BvB them after the one hour grace period of declaring a War is over. More often than not, a team will need to build a new Team Outpost in a galaxy adjacent to the enemy galaxy.