From SC2Pod
The Battlecruiser is the Terran's ultimate weapon. Slow and expensive, it is a flying fortress with massive hit points powerful air and ground attacks. Upgraded with the Yamato Cannon, it can deliver a devestating blast of 260 damage to a single unit. A handful of battlecruisers can take on almost any opposing force.
Lore
The massive, Behemoth-Class Battlecruisers are virtual flying fortresses, built to keep the peace within the Terran Sector. Outfitted with multiple laser batteries and thick NeoSteel armor, these ships are easily the most powerful of the Colonial vessels. Many Colonial generals use Battlecruisers as their command centers during long space campaigns.
Yamato Cannon
Recent research has also led to the development of the devastating Yamato Cannon, a terrifying weapon that uses an intense magnetic field to focus a small nuclear explosion into a cohesive beam of energy. The Cannon requires a huge energy reserve to fire, but its effects are impressive, to say the least. Terran engineers are currently working overtime to retrofit existing Battlecruisers with Yamato devices, but many older ships are still in service.
Weapons
Abilities
Upgrades
StarCraft 2
The Battlecruiser's StarCraft 2 model
The Battlecruiser has returned and is even more powerful in StarCraft 2. It now has even more hit points, and new specialized weapons and abilities. Rather than receiving a universal upgrade, each Battlecruiser must now individually fit itself with a Yamato Cannon, Missile Barrage, or Defensive Matrix. These changes are permanent, so the player must choose the right weapon for the right situation.