Trion Worlds has released the latest Feature Spotlight post that talks Devil Form in upcoming action MMO Devilian. It's basically a character transformation system that grants your character additional power in the battlefield. In Devilian you will collect devil souls by defeating them. "Devil Souls can be slowly earned from defeating normal enemies, and larger amounts are earned as rewards from Dungeons and PvP Battlefields," according to Trion Worlds.
When you have enough devil souls you can choose to turn to devil form for powerful abilities. It's a strategic option in PvE because you can't maintain devil form forever and it could mean big difference when to transform. In PvP or some particular boss fights, on the other hand, you are always in devil form.
Devil form has a distinct set of abilities and its own unique equipment with which to battle. You can also spend collected Devil Souls to level up your Devil form. As you challenge players in Battlefields or make your way through the 100+ level Abyssal Tower, you’ll earn tokens that can be redeemed for powerful Devil form gear. This gear can also be upgraded with enchantments, which allows you a greater level of customization as you take on new challenges.