Effusia is the name given to the distilled essence of the Saroff, the beings that pierced the Ethereal Veil long ago and began an invasion of the world. Those responsible for slaying a Saroff, no easy task, found they were able to absorb the Effusia into themselves, gaining formidable, reality-altering powers. It can be put to a near infinite number of uses, from throwing bolts of lightning at one's enemies to healing the wounded to fertilizing a farmer's crops and more.
Effusia is not expended when it is used. Instead, the more Effusia you gather, the more powerful you become. You dictate how the Effusia affects you, whether you wish to store it as potential magical energy, physical power, or otherwise. When you make use of Effusia by casting spells, it drains your stamina in the same way a physical attack might, though the amount of fatigue Effusia usage causes is much greater, thus much more dangerous.
Effusia, through a Lich's eyes as it is normally invisible to others', appears as a dense, swirling fog of paled turquoise color. When a living thing containing Effusia dies, the Effusia escapes the newly created corpse and forms a pool closely around its former home.