Tigris

A extremely supermassive blimp. Nothing (just about) can defeat it. Inside is where most of the Extreme and Nearly Impossible tracks might occur, since this is as deep into Bloon territory as you can get. It is ruled with titanium fists by Helios, secretary of war Xorcor (the Apopalypse Bloon) and secretary of defense Fractal (the Genesis Bloon).