The beserker form is an illusive state of power available to both Windragons and Blazedragons. While Shiron can be seen with one in the opening credits, he never uses it in any episodes. Though manga Shiron does indeed use it. Greedo however has never been seen with it. Unless you look at other media like the toys and games. Stronger than a base blazedragon, yet weaker than a Command, the berserk forms I imagine, prioritize power and speed for a legendz. Often connected to the user's rage. For Brimstone the form keeps the basic body shape but adds a number of cosmetic changes. He gets an extra chest plate. His fur tuffs on his clothing grow and turn hot red. Extra ports on his leg buckles that spew fire and he has chains wrapped around his arms.