The Egg Libra is the fourth boss fight for Sonic and first boss fight for Blaze in Sonic Rush for the Nintendo DS. On a circular, roulette-like platform looking out onto the neon skyline of Night Carnival, the heroes face off against Dr. Robotnik or Dr. Nega, who control this odd cross between a carousel and a grammophone needle.
As usual in Sonic Rush, here both the Eggmen have the keys to this ride; Blaze fights the machine under the control of Ivo Robotnik while Sonic battles Eggman Nega in the same vehicle.
The fight takes place on a circular arena with the screen following the player as they move. The Libra's components spin clockwise above the player; one part is the control pod to which damage is dealt, while the other is an electrified metal sphere which can zap the floor with lightning.
- The rotating sphere represents both the greatest danger and greatest opportunity in this boss. The player can be hit simply by running underneath it on occasion, as zaps of lightning blast the floor from time to time. Usually, the sphere is surrounded by crackling electricity, but when it discharges, it's vulnerable. Spin attacking it causes the sphere to raise up into the air - and, as a consequence, lower down the control pod that sits at the other end of the T-beam. Run round and smack the module to chip down the boss' health.
- Another way of damaging the Libra is to use the small green rover robots which the electric sphere sometimes drops. Destroying them catapults you high up into the air, allowing you to hit the control module even when it's raised up.
- As its health gets low, the electric sphere will start slamming into the floor. Don't get caught underneath - it's instant death. The impact sends a pair of shockwaves out along the circular platform, so be ready to jump over them.
Eight hits defeats the machine. In Blaze's fight, Robotnik drops a Sol Emerald while fleeing in the aftermath of the battle.