Omega Arm
From Sonic Retro
Omega Arm is E-123 Omega's version of the Circular Attack move for Team Dark in Sonic Heroes. After firing both Rouge and Shadow towards enemies with an aerial Fire Launcher, pressing 
again will see the robot break out this final radius-of-effect weapons fire which is potentially Team Dark's strongest bar Chaos Inferno.
The strength and nature of an Omega Arm depends on how many Power Cores E-123 has collected:
- First level up: Omega fires machine gun bullets from his arm cannons.
- Second level up: Omega activates the flamethrowers in his arm cannons.
- Third level up: Omega fires missiles from his arm cannons.