Pencil sketch with Photoshop color and shading. The Flying Polyps are opening a hole in the sky, and letting in noxious vapors from God knows where or when. The Flying Polyps are described as being similar to the Cthulhu Spawn in not being made of ordinary matter, and displaying a distressing plasticity.
Sketch for flying polyp. I deliberately gave them Cthulhuish affinities. So many artists who've drawn the polyps obviously did not read even the scant descriptions provided by Lovecraft. Here's a hint: when the creature is described as EYELESS, making eyeballs the main feature of its skin is counterproductive.
Update: reenvisioned Polyps, and did a new sketch of battle.