The Borg Cube is an Epic ship from Operations 28, with 18 tiers across 90 levels. Its strength is tied to how far you have progressed your faction ships, so it grows alongside your fleet instead of replacing it. You can own and upgrade up to three Cubes per commander.
Once charged, the Beam fires at a target anywhere in the same system without you entering combat. It deals damage straight to hull and bypasses all defenses. It cannot be used against player stations, Alliance Starbases or Armada targets. The Beam charges from HHP damage you deal in ordinary combat. It has diminishing returns against targets above your level, so use it on hostiles near or below your level.
Destroying a PVE target with the Cutting Beam awards Technological Distinctiveness. It refines into Shape Memory Alloy, which tiers up the Cube, and Advanced Cybernetics, which progresses the Cube's nodes in the Ex-Borg research tree. So you fight with the Cube to earn the material that upgrades it.
A second or third Cube needs a Borg Data Node from one of the three main factions. You earn each Node by hitting a tier milestone on a specific faction ship. If a prompt says a requirement is unmet, it names a different faction ship to bring up to that tier. A ship you used for your first Data Node cannot be reused for the second.
Officers and research for your other ships do not change the Cutting Beam's damage or charge rate. Only the Cube's own tier does. A Cube you have never upgraded has no repair cost, so leaving one at tier 1 is a real option if you are not ready to invest.