Level One
Ludger can transform when the Chromatus Gauge is at level one by pressing L3 + R3. A transformation that that consumes one level of the chromatus gauge will increase defensive capabilities and will prevent you from staggering from enemy attacks. This is very useful when dealing with powerful enemies. At the time of transformation, enemy artes will be cancelled, so it can be helpful to transform when your allies are in trouble.
 Level Two
A transformation that consumes two levels of the Chromatus Gauge will put Ludger in a state when he has heightened attack capabilities. All his attacks will receive a power boost, and he can enact mystic artes at will. This is useful when fighting enemies that are difficult even after transformation.
Enacting Mystic Artes while transformed: Hold X after pressing L1+X
 Level Three
In a transformation that consumes three levels of the chromatus gauge, all your attacks with X will produce shadows which will double your total number of hits. The capabilities of your attacks with O also increase, allowing you to fight on a level playing field with even the toughest enemies.
 Level Four
All of your attacks will be increased to their utmost limit in a transformation that consumes four levels of the chromatus gauge. There are several other powerful effects you can make use of in this mode. For example, by performing a taunt in this state, you can even spend twice as much time transformed depending on your skill effects. Your mystic artes will be more powerful than ever before. It also grants Ludger access to the Endless Waltz Mystic Arte.
 Known Chromatus Users
Related ThreadsChromatus Tutorial - last post by @ Sep 8, 2014
Chromatus - last post by @ Aug 28, 2014