The DLC can be picked up through Steam right now until October 29th, at which point it will go to its regular price of $7.99 (USD). Mike Simpson from Creative Assembly explains why this pack is free for a limited time.
"We are going to continue to work on gameplay feature balancing with our community who have been hugely helpful in feeding back on the game," he said. "Offering this DLC for free for the first week it's on sale is a celebration and a small thank you to them for helping us make this the biggest TW yet."