Tar Pits

The  is a limited-time premium building that was released on February 18, 2015, as part of the Superheroes 2015 Event. Upon completion, Petroleus Rex is unlocked.

It was re-released on June 20, 2016 for the Superheroes 2016 Event. It returned again on September 12, 2018 during the Super Powers 2018 Event. It was a possible prize in the Mystery Box The Sequel.

Regular
Petroleus Rex
 * Refuel - 8h

Trivia

 * On Bloons Tower Defense 5 there is a track called Tar Pits.