Here is our Mighty Eagle Total Destruction video walkthrough for Angry Birds Bad Piggies level 21-12. (If you’re looking for the 3-star walkthrough video, click here.)
Fire Big Brother into the bottom of the leftmost tower. Bomb the rubble with the White bird, then launch the sardine can head-on into the second-to-last tower. The can should fall towards the base, allowing Mighty to destroy nearly everything. If you have an alternate strategy please feel free to leave a detailed comment below.