Cavity

 is a Tier 5 Tank that upgrades from Thunder, Manager and Minihelix at level 60.

Design
The greatly resembles the Thunder but with another identical barrel added to it. It is added to the tip of its outermost barrel, making it resemble a Minigun-like arrangement of Thunder barrels. It also retains Thunder's triangular topper.

Technical
Befitting its branches, the Cavity can become invisible by staying still.