Dragon a.k.a. The flying fortress it the heaviest and most dreadful of all aircrafts.
It can withstand incredible amounts of damage, making it virtually impossible to destroy without fighters or heavy AA like Mercuries or Screamers. It flies slowly, but leaves not a single living thing behind. With three independent heavy laser turrets it can obliterate whole armies of light units and deal significant damage even to T3 Mechs. Considered an endgame unit due to its super high cost.
Most often used for defending from ground units. In special cases, when your opponent has tons of ground AA, and you can’t get through with your bombers, Dragons make a good choice for a striking unit.