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Runes in OP read, from top to bottom: "strength," "the self", "seperation", and "signals".
Single frame of pyramid guy hidden in OP:
Next to Grunkle Stan's symbol in the ring of symbols is some Cesarian Cypher code. It translates to "Stan is not what he seems."
Pyramid Guy himself is an Eye of Providence. The eye of providence was used in medieval Christianity to symbolize the holy trinity and the omniscience of God. It is also popularly associated with Freemasonry.
Symbols in the circle, going clockwise:
The middle-right symbol is seen on Grunkle Stan's fez. It resembles a simplified, rotated Shriner logo. The Shriners are a subset of the Freemasons, known to wear red fezzes with their organization's logo stamped on them.
Next is the pine tree, seen on Dipper's hat that he obtains in the first episode.
Next is a pentacle with an eye in the center, seen on Lil' Gideon's cape and tent. The symbolism of this is kind of obvious.
Next is a six-fingered hand, seen on The Books owned by Dipper and Lil' Gideon.
Next is a llama, worn on a llama-hair sweater by Mabel. Wax Larry King tells her to wear the llama sweater because "Llamas are nature's greatest warriors."
The shooting star symbol is also worn by Mabel.
The stitched heart is worn by Robbie, a teenager introduced in The Inconveniencing.
Not sure who the glasses represent.
The question mark could either represent Soos or The Mystery Shack.
The ice symbol is a mystery. Ice bags first appear in the show in The Inconveniencing.
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