The Overdrive Invoke System (O.I.S.) is a feature introduced in its only appearance in Mega Man ZX
The Overdrive Invoke System is a special ability that all known Biometals except Model X and A possess. When activated, the user emits a colored, resonating aura not unlike those seen in Elpizo and Omega. During this state, the user's Biometal is literally in overdrive, pushing the Biometal's powers to their fullest for a limited time to increase their powers until they're burned out and is typically used as a last resort.
O.I.S. is activated during gameplay by pressing X, causing the character to produce an aura around them. During this time, certain attacks and attributes are enhanced to dramatically boost performance. The drawback however is constant Weapon Energy use and certain attacks can drain it even faster. At any time, the Overdrive can be turned off to preserve energy, so it is wise to use it in short bursts if necessary.
- Model ZX (manga only) - Enhances the Z-Saber, enlarging the blade several times its size and granting it enough power to destroy
Serpent with one strike. The hair flares up to resemble wings and produces a halo behind him, identical to when Vent/Aile first transformed with Model ZX and the body produces a vibrant glow.
- Model HX - Enhances the sabers with the Thunder element, stunning enemies with an electrical charge. Produces a green aura.
- Model FX - Enhances the buster cannons with the Fire element, igniting enemies with every shot. Produces an orange aura.
- Model LX - Enhances the halberd with the Ice element, freezing enemies solid with each hit. Produces a light blue aura.
- Model PX - No elemental properties, but the kunais themselves become more powerful. It also grants the Shadow Dash ability which grants the user invincibility whenever dashing. Produces a purple aura.
- Model W - No elemental properties, but enhances the strength, range and speed of the user's attacks. Only demonstrated by Serpent. Produces a violet aura.
- Model OX - Infinite Overdrive usage. Grants a myriad of attacks, enhancing the OX Saber with special attacks using all three elements, instant charged shots with the OX Buster and access to Giga Crushes borrowed from Omega Zero. Produces a crimson aura.