Ch 198: Golden Seed
"Soul Attacks requires Soul Force as the source of energy to work. And just like a soul attack, every skill you or anyone use consumes energy to execute. No matter what kind of skill, it needs certain energy as a medium to execute."
"Combat skills require Chaos Energy, demonic skills consume demonic energy and the same goes for the abyssal skills which consume abyssal energy. Then there is Blood Energy which is required to execute skills that direct have effects on blood or are related to blood. Even the most primitive physical attack consumes a person's stamina as the source of energy."