Call of Cthulhu: Skullhouse
The Triskelion symbol with an eye at its center was favored by Charles Drood and other members of the Chapel of Contemplation. By extension, the symbol could be specific to Tsathoggua, though this has not been confirmed.
Triskelions activated via the Sigil spell grant the operator the ability to remotely influence victims near the symbol.
The effects of a triskelion are easily disrupted by marring the symbol.