The Seal of N'gah

"Again thanking you in Tsathoggua’s name for the recent shipment, & hoping to see more items from your pen ere long, I append the Elder Sign & the Seal of N’gah, given in the Dark Cycle of Y’hu."
From a letter by H.P Lovecraft to C.A. Smith

For more on this rare Lovecraft creation see here [link]