Gunbreaker

Gunbreaker focuses on cooldown management to maximize damage within every cast of No Mercy. It is unique in that it is the only tank that has GCD-based cooldowns such as Gnashing Fang or Double Down, making it slightly stricter in exchange for slightly higher DPS. Gunbreaker’s unique mitigation cooldowns can grant high HP sustain and/or recovery for individual targets through actions such as Aurora or Heart of Corundum.

Gearing
Stats & Materia
Item Level > Critical Hit > Direct Hit > Determination > Tenacity. Replace with SKS (as required for GCD tier) in reverse order.