In StarCraft II, the Terran battlecruiser ability that fires a powerful beam at one target is Yamato Cannon.
Yamato Cannon is a high-damage ability associated with the Terran battlecruiser, the Terrans’ largest standard capital ship. It is designed to eliminate or severely damage a valuable target, such as an enemy structure or a powerful combat unit, before the battlecruiser continues fighting with its normal weapons.
The ability is named after the Japanese battleship Yamato, one of the largest battleships ever constructed. StarCraft’s Terran technology frequently uses military terminology and naval imagery, and the battlecruiser itself is presented as a massive warship rather than merely a flying combat unit.
Yamato Cannon is distinct from a Nuclear Strike, which requires a Ghost and a nuclear missile. The battlecruiser’s other abilities and upgrades vary by StarCraft II version and mode, but Yamato Cannon remains its signature long-range bombardment attack.