At first glance there seems to be just one Yog Conspiracy Card (The Ritual Conspiracy).
Well, there is also 'The Great Design' from the last AP in the Revelations cycle (i.e. the most recent one). It's quite specific, though, since it's only useful if you are going to play Elder Things.
I don't think you should use more than three conspiracies in one deck. After all you'll add them since you intend to win them more easily than your opponent, so you shouldn't need more than three, right? Instead add more ways to search your deck for them and bring them into play, i.e. I'd add both Amaranth and the Red-Gloved Man!
P.S.: I supposed you used CardgameDB to search for conspiracies? 'The Great Design' will show up if you search for story cards - it's tagged wrong currently.