Invariable

The Invariable is a tier 5 tank that upgrades from Twin Builder, Invariant, Dual Builder at level 60.

Design
The Invariable looks like the 3wwww, as its almost as small as a square in the grid. It has a square as a body.

Upgrades
The Invariable can upgrades from, and  at level 60. Since the Invariable is tier 5 tank, it cannot upgrades any further.