Special is a battle command that turns all party members into Dragoons. The party member that activates it, receives their corresponding Element Dimension and also is guaranteed a perfect for their attack command along with 50% status power up. In order to activate this command all Dragoons in the active party must have their spirit level maxed out.
Bonus damage and damage reduction will of course be implemented as stated in the Element Dimension article, but there is one additional defensive benefit. From the time the first Dragoon takes their turn until the third one takes their turn, they receive the Dragoon bonus. That amount of defense for that amount of time is "free", compared with activating their Dragoons one after the other.