Ironsight

 is a Tier 5 Tank that upgrades from Watcher and Iron at level 60.

Design
looks identical to Watcher, but with its shell recolored to match the color of Iron.

Technical
Being a simple combination of its branches, the can zoom out with right click and is immune to all debuffs.

Trivia

 * This tank's name is a pun on real life iron sights used to aim guns. Ironically, being a Smasher branch, this tank has no guns to speak of whatsoever.
 * It was also named this way for, obviously, being an Iron branch, and it's ability to scope, which is where the "sight" part derives from.