Ideas for Borg avatar.  I thought you could use the Bord Queen and Locutus.  There bonus could be for example the Borg Queen could make diamonds stronger and Transworp technology. Then Locutus could make cubes stronger and faster as well as Assimilation bonuses where they can copy other races special abilities and not need to research them. 

The Borg should also have a special ability that allows them to adapt to all weapons for a short time. For example the Romulan can attack while cloaked and the Klingon has stronger weapons.