Across the games, there are a number of glyphs/symbols used in association with the Null. The exact symbology seems to vary from game-to-game, but there are a few which are reoccurring and can be said to have meanings. Each game seems to introduce at least one new symbol to the series, many of which are variations on known geometric patterns, such as Metatron's Cube.
Different symbols would appear to have different properties, though the nuances of the differences between them are still unknown.
Symbols used to contain Maggy's soul within the fortune telling booth at Grey Holm.
Not used as frequently as the other two hexagonal patterns, but is also a variation on the same root pattern. Used often in conjunction with the other two.
Metatron's Cube
Metatron's Cube as it appears on the back of the Tarot Cards.
Same symbols are found in the binding circles surrounding Maggy's tarot machine and are gradually added as she resists The Craftsman's attempts to contain her.