An idea came up sometime ago and based on the idea of Helminth and videos where WarFrames used unique abilities not seen in game, idea is have more then 4 abilities but have them hidden away for dangers of pushing themselves too far and limit there effectives in battle

Chroma Hidden Abilities:

Hidden 1: ElemBall, Launch and Ball of Elemental Energy at your foes: FireBall = Blast Radius, ToxinBall = Damaging Floor, ShockBall = Stun Single Target, IceBall = Punch Through

Hidden 2: Touch of Drakes, Focus Energy To Boost Teammates

Hidden 3: Burst Blast, Unleash and Wave of Elemental Energy

Hidden 4: True Dragoon, Become more like the Anicent Beast with improved Abilities, Passive and Enchanted Weapons, Team Supporting

Hidden Passive(Causes why not XP): Gain 10%-15% Added Element Resist with Element Type