RK-X

The RK-X is a tiered boss. It is commonly found in Boss Rush as one of the waves.

History
They were added to the game with the boss rush.

Spawning
RK-1 always spawns at Boss rush Wave 15 but RK-2 and higher have not been seen in-game.

Strategy
It is a good idea to attack the RK-1 with an Incognito. The RK-1 has sufficiently low health for you to kill it quickly.