First of all, Warhammer Quest is a great game. You should go get it if you haven't already, even if you missed out on it when it was free last week. But regardless of whether or not you were able to take advantage of the sale, there's a totally new sale you can take advantage of this weekend.
From now through Sunday, pretty much all of the game's in-app purchases are on sale for $0.99 each. That means new regions, enemies, heroes, etc. You can grab them all for a very reasonable price.
Warhammer Quest is available on the App Store for its more typical (and still quite worthwhile) price of $4.99.