Excellent art and writing that combines eldritch Cthulhu and King in Yellow energy with knights! In Pathfinder 1e I remember there being a Hastur cleric build where you get to engrave the yellow sign to inflict madness, and this very much reminds me of that. It allows players a lot of flexibility with how/where they place it or leave it as a trap. The Alien Seer is also really fun, I love that almost science fiction Call of Cthulhu eldritch horror in fantasy so much.
Thank you so much! My aim was to emulate occult-character archetypes from the Cthulhu Mythos, so Pathfinder's Hastur cleric is in line, yes! In the Cthulhu Mythos lore, The Elder Sign can be seen as the reverse Yellow Sign, which affects the Eldritch Horrors and other otherworldly creatures. And glad you like the Alien Seer! I've been in a Weird Fiction science fantasy mood, so I'm glad you like it!