The Voice of the World is a phenomenon present in all places. It serves to announce important events such as the acquisition of skills, racial evolution, obtaining a demon seed or hero's egg, and the activation of some skills. When active, it will echo within the mind of all parties relevant to the event in question. Skills may make use of the Voice of the World to communicate prompts for activation to their users.
You now have the ability to hear the Voice of the World which grants you the capacity to develop new skills and abilities based on your personal growth. Your skills will be inscribed onto your soul or material body. Once you obtain a skill it may be used instinctively without practice, however practice and experience can improve the efficiency and effectiveness of your skills. The Voice of the World will allow you to recast all of your existing powers and abilities as skills.
Intrinsic skills encompass skills and abilities that are common to members of the user's species.
Common skills are relatively low powered and not unexpected to be encountered, such as telepathy or self-regeneration.
Extra skills stand at several magnitudes higher in terms of power and efficiency than common skills. They might exist as intrinsic skills for particularly powerful species or as sub-skills for unique and ultimate skills.
Unique skills stand at the next evolutionary stage after extra skills, and are unique to their user. They are frequently made of a collection of subskills of common or extra rank, or might have a subskill unique to that skill. They are described as the "shape of the mind" and thus require their user to have strong desires to acquire them. Some unique skills may possess potency to rival ultimate skills, the next stage of evolution.
Ultimate skills are the final stage of evolution for skills, in general. They grant their user's ultimate power to control the laws of nature within the confines of the skill. Ultimate skills can be achieved by bringing one's unique skills beyond their limit. Only an ultimate skill can counter specific effects of another ultimate skill.
Resistance skills can be intrinsic skills or acquired through long term exposure to attacks of that type, such as resistance to elemental magic or temperature fluctuations.
World System Skills are skills that allow the user to create a unique world and are exclusively found as subskills of ultimate skills.