Heavy ARTILLERY. Long range support bombard.
Offense: Like most artillery keep behind a wall of units to provide support fire. This has really good range for such a cheap artillery but the fire rate is pretty slow. Still with the cost you can spam a lot of them as long as you can keep the front lines far enough ahead of them. Great support unit.
Defense: Attack with helicopters or rush it with tanks as it doesn't have too much health and is fairly easy to destroy. Just don't let it get behind a wall of units otherwise it will be able to pound you since there aren't many units with its range.
This is the long range variant and also being Ultra rare probably has the highest damage output