- "Use the Spirit of Fire's awesome Mass Accelerator Cannon to incinerate enemy troops."
- — In-game description.
The MAC Blast consists of a bombardment by the Spirit of Fire from orbit of an area of the ground, using its ship-mounted Magnetic Accelerator Cannon. These strikes are capable of devastating relatively large areas, and can destroy even Covenant Scarab walkers with their strength.
Although powerful, it is theorized that a real-life strike of similar proportions would rival nuclear warheads in their devastation. Instead, the MAC Blast causes far less damage, though more than enough for the UNSC's needs. The Spirit of Fire may use specially designed MAC shells, either smaller or lighter, for orbital bombardment, to prevent collateral damage to allied forces, or more likely, the rounds are being fired at a lower charge in order to fire so many rounds so rapidly.