In the Robo Rumble Event, three players battle against many waves of robot enemies to protect a safe. The first wave starts at 2 seconds and each wave lasts 13 seconds after that. There are four type of robots, a "melee robot" with high hitpoints but low range, a "shooter robot" with low hitpoints but high range, a "mini robot" with low hitpoints but high speed, and a "boss robot" with very high hitpoints and damage. The boss robot has a melee attack or can shoot rockets, and one arrives as the only robot every 7 waves. After a boss robot arrives, all robots after that have increased health and damage. This is an unranked mode, so Trophies cannot be earned or lost.
- Throwers like Barley and Dynamike can take out swarms of robots behind the cover of a wall.
- Healers like Pam and Poco can help avoid the slow respawn timer.
- Do not approach the robot spawn point, or the robots will begin spawning next to your safe; they spawn wherever players aren't present.
- Respawn time is 10 seconds instead of the normal 5, so it is important to stay alive.