Firzen is an effect of combining Firen and Freeze.
To obtain it, both have to be in the same team and have to have no more than 25% life points.
When they come close to each other, there is an explosion and Firzen appears.
If you want ot change Louis into Louis EX, the first one he has to have no more than 33% life points.
At that point press D+J+A.
When Julian do Big Bang (D+up+J) Firen must do Explosion.
Then Firen change into Julian.
When Rudolf hold enemy, he can change into him.
You must hold enemy and push D+J+A. You can return to Rudolf by pushing D+J+A.