Terran Guide – How to Play Well Against Zerglings, Banelings, and Mutalisks
This seems to be one of the most difficult strategies to go up against for most terran players. Zerglings, banelings, and mutalisks are very powerful together. Mutalisks are tough to defend against as it is. They are the fastest air units in the game that can attack both ground and air units.
Banelings do very well against marines. Zerglings are very fast and can surround your army to trap them while the banelings clean up your army.
To counter these units you must practice controlling your army aggressively. When you have a large bio army (an army of marines and marauders) and you see banelings rolling your way you need to split them up to make their attack as ineffective as possible.
Also make sure to include thors in your army to absorb the banelings explosions and to fire at the mutalisks. Thors have splash damage does great against mutalisks. You just have to watch out for their “magic box” maneuver. For more strategies get this starcraft 2 guide.