Borg tactical cube

The Borg Class IV Tactical Cube was a powerful combat vessel utilized by the Borg Collective. The tactical cube differs from the standard Borg cube in several ways, the most notable being the extensive hull armor that covers a large portion of the exterior hull of the ship. The interior is also slightly altered from what is known of Borg 'architecture'. The vessel's central plexus is protected by multi-regenerative security fields.

Only one such vessel has thus far been observed by Starfleet - by the USS Voyager in 2376. The tactical cube was later caused to self-destruct by the Borg Queen during a brief civil war within the Collective. (VOY: "Unimatrix Zero, Part I & Part II")

The Tacticla Cube employs two special weapons: The Holding Beam restricts movement of an enemy vessel and transfers drones directly onto the enemy ship. This beam is available on all Cube-class ships once you posses a Technology Assimilator. The beam immobilizes the target vessel and assimilates a special weapon from the target vessel (assuming one is present), giving that Cube-class ship the ability to use that special weapon. If more than one special weapon is present on the target vessel, then a special weapon is assimilated at random. Assimilating a special weapon and then bringing that Cube to a technology assimilator station can equip all Cube-class ships in your fleet with that special weapon.(TNG game: Armada II)
 * Holding Beam
 * Technology Assimilation Beam