Thanks @marcoriccardi! :D I've noticed that dealings with cosmic entities usually bring torment, insanity, death, and destruction, sometimes on an apocalyptic scale. Since the orcs were already facing annihilation, I thought it would be interesting for them to invoke Yog-Sothoth as a kind of last-ditch Doomsday weapon.

After reading your comment, I did some research and I realized I'd made a mistake in referring to Yog-Sothoth as an Old One. It's been a few years since I read those stories! :) I've changed a couple of phrases in the text to more accurately reflect Yog-Sothoth's standing within the Mythos. Thanks again for the comment and also for your point about the Great Old Ones! Both are very much appreciated!