The Iron Ball Eggmobile is a recurring boss in Sonic Runners Adventure. It can be fought with any character in the game at the end of each playable chapter.
The Iron Ball Eggmobile is fought on four separate occasions. During each battle, the player automatically chases after Dr. Eggman in his Eggmobile. However, the Eggmobile usually stays out of the player's reach, meaning it cannot be attacked head-on.
In Green Hill, Eggman attacks by dropping iron balls that fall directly down on the path. Simply jump over them when they approach the playable character. Meanwhile, red drill missiles will fly across the screen from the right side which the player has to dodge too. After launching a few attacks, Eggman will then charge towards the playable character. Hit the Eggmobile when it gets close with a Spin Jump to damage Eggman and make him drop both Rings and Super Rings. To defeat this boss, the player must hit Eggman a total of five times.
In Desert Ruins, the battle proceeds like a sped up version of that in Green Hill. This time around, however, when Eggman drops iron balls, they will sometimes bounce towards the playable characters at a set height. Simply stay on the ground to avoid these iron balls. Eggman is also sometimes drop yellow balls that bounce and do harm like the iron balls. By Spin Jumping into the yellow balls, the player can knock them back at the Eggmobile to damage Eggman and make him drop both Rings and Super Rings. To defeat this boss, the player must hit Eggman a total of seven times.
In Lava Mountain, the battle follows the same format as that in Desert Ruins, but sped even more up. In addition, the different balls that Eggman drops during the battle now bounce at varying heights. Those bouncing low must be jumped over to be dodged, while those bouncing high must be run past below to be dodged. To defeat this boss, the player must hit Eggman a total of nine times.
In Sky Sanctuary, the battle reuses its patterns from Lava Mountain at maximum speed. In addition, Eggman will now deploy iron balls that can be suspended in midair. He can also drop up to two bouncing iron balls in succession that always bounce in the same manner as each other. To defeat this boss, the player must hit Eggman a total of eleven times.