If you are playing against Zerg these tactic will be very efficient to defeat the enemy easily.By building half or one Fleet of Battlecruisers you can destroy any Zerg unit without loss but here the important things are always reparing the Battlecruisers by loading a dropship with SCVs and using Yomato Gun ability to eridicate Zerg Acid Spores.Because these spores can be very dangerous against any air unit of the Terran so you must rest your fleet if there is not enough mana.The Teran Battlecruiser’s maybe best property is its high and fast firing weapon which can stop the dcourge trouble.Genarally the heavy ship’s biggest disadvantage is its speed which makes them very weak essepically Scourges.For instance carriers can be killed by lots of scourges if the player is not enough skilled.But Battlecruiser has a natural killing capacity which is superior to light units like scourges marines.You must remember that this tactic is useless against Protoss.Because Dragoons,Psionic Storms,Scouts,Carriers and Dark Archons can easily prevent your Battlecruiser assault.So you can make these units against Terrans. (moderate efficiency you’ll have)But the Zerg defence will be useless against a fleet of Battlecruiser with the aid of repair and Yomato usage.You must try it, it is a fun!