Yog-Sothoth knows the gate. Yog-Sothoth is the gate. Yog-Sothoth is the key and guardian of the gate.
One might be surprised that I intend to include H.P. Lovecraft's insidious creation, Yog-Sothoth, in my Erimia campaign. When I first considered the idea, I was a tad bit uncomfortable. Reading Lovecraft's own description, one is struck by how powerful Yog Sothoth seems:
It was an All-in-One and One-in-All of limitless being and self — not merely a thing of one Space-Time continuum, but allied to the ultimate animating essence of existence's whole unbounded sweep — the last, utter sweep which has no confines and which outreaches fancy and mathematics alike. It was perhaps that which certain secret cults of earth have whispered of as YOG-SOTHOTH, and which has been a deity under other names; that which the crustaceans of Yuggoth worship as the Beyond-One, and which the vaporous brains of the spiral nebulae know by an untranslatable Sign...
However, upon a bit of reflection, I realized that from a Christian point of view, Yog-Sothoth is a brilliant cipher for the Devil. According to Christian cosmology, the Devil is an angel who rebelled against God:
How you are fallen from heaven, O Day Star, son of Dawn! How you are cut down to the ground, you who laid the nations low! You said in your heart, "I will ascend to heaven; I will raise my throne above the stars of God; I will sit on the mount of assembly on the heights of Zaphon; I will ascend to the tops of the clouds, I will make myself like the Most High." (Isaiah 14:12-14)
The word "angel" itself means messenger, and they are also known by the title "the bodiless powers." Thus, they are part of the invisible creation. In his pride, the Devil sought to be greater than God. He tried to wrest power from God by by destroying the image of God in humanity. He first tried to destroy the relationship of God and humanity through tempting Adam and Eve to eat the fruit. Then he tried to destroy humanity's relationship to itself by tempting Cain to murder his brother Abel. Though he ultimately failed to destroy the image and likeness of God within us, he did succeed in introducing sin and death into the world. In so doing, he gained control of humanity through death and sin.
Thus, when Yog-Sothoth is described as one with space and time and yet somehow beyond space and time, this describes the Devil's being as a bodiless power. He is part of creation — space and time — at yet can move through space and time in a way incomprehensible to us — he is part of the invisible creation. Lovecraft says of Yog-Sothoth that:
he knows where the Old Ones broke through of old, and where They shall break through again. He knows where They have trod earth's fields, and where They still tread them, and why no one can behold Them as They tread.
The Old Ones become a cipher for the fallen angels that the Devil took with him in his rebellion. They broke through when humanity turned its back on God, and they strive for control of creation — a task they can never succeed at because they are part of creation. God, who is by nature something completely other than creation, sustains creation by His will. The irony is that without God's will, creation will return to the nothingness from which God created it — should the Devil and his fallen angels ever succeed in wresting complete control from God, they will cease to exist.
There are also Gnostic overtones with the description of Yog-Sothoth. Gnosticism is a heresy that claims that the creator God is really a selfish and evil demiurge that has trapped the true essence of human beings in creation. Only through "secret knowledge" does one discover their "true nature" as a spark of the "true god." One aspect that I love about Lovecraft's description of the "secret knowledge" of the Old Ones is that it leads to insanity — a fair description of anyone who willingly chooses nothingness over the eternity of life that God offers His creation.
Thus, Yog-Sothoth and the secret knowledge he offers is the patron of the forces of Chaos that inhabit the wilderness of Erimia.