Battlecruisers form the core of Human fleets. Their huge computing clusters make their AIs essential parts of battlefield command, arguably equivalent to admirals in their own right. Their spinally-mounted SHERMAN Cannons are one of the few non-magical means of destroying Cephalopod capital ships, and the goal of any engagement is to start using them mercilessly, but even before then they perform vital fire control and support.
They are kilometers in length, so large that moving internally often requires the use of an FTT. They are correspondingly very expensive to produce; at the Battle of Orpheus, one of the largest fleets ever fielded counted just fifteen among its number.
While often overshadowed by Blink Cannons and Heavy Carriers, a Cephalopod battlecruiser is no less of a weapon than its human counterpart. Its Eviscerator laser is more powerful than the SHERMAN, and often sees use in planetary bombardment. In fleet combat, it is often used to delay Human fleets from closing in on the more vulnerable capital ships.