A Higher Power gains power by acquiring devotees, worshipers, or followers. This does not have to be in a religious sense, only that they pay homage to a Higher Power by calling on them for strength, intelligence, good luck, fertility, power of fire or other element, or anything else matching a deity's Divine Domains. After gaining sufficient power, by way of attracting mortal followers, Higher Powers are ranked up in Divine Power. This provides more Divine Domains, prestige, and for some an ego boost.
One stipulation of being a Higher Power is that to go beyond the status of demi-power, a demigod, they must leave the Mortal Systems. This is the first ruling of the long treatise called the Rule of Divine Governance. Enacted in the God Era, it cordoned off the Mortal Systems from those that decided to rise to the ranks of divine leaders. In simplest terms, it says you cannot be a deity and enter or directly help the Mortal Systems. The rules are lengthy, with one preventing a recently made undead from becoming a servant to a Higher Power; like what happen with Lady Hunger.
Most Higher Powers that enter a Mortal System, immediately suffers the loss of one domain, and another each day thereafter. They also suffer the loss of powers, vitality and strength, so that over a few days a greater god could descend to the level of a demigod. The few that are excluded from this Rule of Divine Governance were allowed to remain on Bal-Kriav after the Creation War. Bruh Kreniik gave them a pass so long as they marshaled their armies for the shock that would come after the Abyssal Release (7777 DE - 8777 DE). The Higher Powers not subject to this rule are Geb and Surtur. In the Demon Spawn War, these two primordials joined the Quara'tun Covenant in their fight against the demon hordes invading the Quara'tun System.
Another case of a Higher Power living on a mortal world is Lokestant. A demigod, not as restricted by the Rule of Divine Governance, she makes her home on the world Bal-Kriav. It is thought that she has been given a temporary pass by The Balance for her determined efforts to stop the Karnegmoth Cataclysm.
It is thought that Bruh Kreniik created the energy matrix that reduces the power of a Higher Power when entering the Mortal Systems. A few cults, followers of all things Chaos, say that it was Piranoth, the first creator of worlds, as the one behind this. They give no reason, only that it was another of his mistakes that cumulated in the the Abyssal Release.