Description from the publisher:

Cthulhu Wars: Great Old One Pack One adds five new Great Old Ones to Cthulhu Wars, and all five are available to each faction on a first come, first served basis. If you awaken Mother Hydra first, then no one else has access to her...unless they can kill her and reawaken her for themselves. Each Great Old One has its own special ability, plus its own unique spellbook, which is earned separately from your own.

• Abhoth is, of course, the horrible thing which is the source of all uncleanness. When you awaken Abhoth, you gain the power to place Filth tokens around the map. The Filth tokens "fight", participating in battles in their areas, and any damage they inflict goes onto both sides of the battle. However, since the Filth itself is immune, it gradually makes the world a more and more polluted cesspool.

• Chaugnar Faugn gives you the ability to alter the way the Elder Signs work (to your advantage). In addition, he provides you with a new action: Miri Nigri (cost 1) select an area in which you have units; a battle immediately begins there, and all your cultists in the area add +2 to their combat.

• Cthugha is difficult to get as you have to sacrifice a Great Old One, but it changes the way battle results work, allowing you to transform your kills rolled into Elder Signs. Of course, this spares your opponent, but hey, Elder Sign! Also, his spellbook, Fire Vampires, earns you Power for damage inflicted on YOU.

• Mother Hydra gives you the ability to sting your enemy out of the sea, reserving them for your own use. Her Zygote spellbook permits you to spawn multiple cultists at once at a low cost.

• Yig makes your cultists poisonous, so if they're eaten by enemies, those enemies die. In addition, when he earns his spellbook, each turn your foes must decide whether to donate power to you or have you earn doom points.