To use this Arkham Horror card game pack, first make sure you have The Circle Undone expansion. Shuffle the cards in the In the Clutches of Chaos Mythos Pack into the relevant deck. Then, start the game and use the cards as the rules direct. Remember, this pack is designed to be played as part of the cycle, so follow the overall game narrative. Keep the cards in a dry place and away from direct sunlight to prevent damage. When not in use, store them in a proper card sleeve or box to keep them in good condition.