Kingdom Rush ReVengeance - The Original World Campaign (Impossible)

This level is interesting as most of it is easy, while the boss itself is one of the tougher bosses in the game. Therefore my entire strategy was geared towards defeating him: I didn't use any magic towers and relied on strong physical towers in the middle lane + ranged barracks and hero for a bit of help. Thankfully everything went exactly how I envisaged on my first attempt.