Solar Eclipse

Solar Eclipse is a extremely powerful developer-only boss.

Design
It's a black circle with a Xyv Guardian turret on top and a barrel which looks like a Incognito barrel. They both shoot bullets that have the Permanent EMP effect, which permanently stuns tanks.

Technical
Solar Eclipse is is very powerful. The guardian auto-turret shoots bullets extremely high penetration health and crashers with high reload, high initial launch speed, and medium speed. The front cannon shoots EMP upon right-click and doesn't have any left-click ammunition; however, the EMP effect is infinite, though it doesn't have as much range as Surge's EMP shot does. And it has A LOT of health, (100,000) MORE THAN ANY OTHER BOSS IN THE GAME. (For context, Chaos has 10,000 HP)

Countering
Take a group of ideally 4-5 Surges to shoot EMP bullets at the boss, and an Icicle to kill it But you will need 2-4 tanks, ideally Smashers for distraction since it can kill you all before you even get close. İf you can do this, just melt its health without letting it escape from the EMP. Incognito(s) may also be useful since the boss won't notice them. If you can do this before it obliterates you all, congrats - you (and your team) have killed one of the strongest entities in the game.

Trivia

 * This boss doesn't have a AI since the devs are very determined to not make one.