The Aurora God Emperor said this because Fan Lang had indeed rendered an unparalleled service.
All three of the Bug Queen's World-Destroying Martial Prowess had been tampered with by Fan Lang. They either failed to fire or changed their flight paths, greatly helping the Aurora God Kingdom while ruthlessly screwing over the enemy nation.
Fan Lang had seized the chance to tamper with the World-Destroying Martial Prowess during his battle with the Bug Queen herself. During that fight, he injured the Bug Queen and took the opportunity to inject Sparkfire Poison Plague into her body.
The Bug Queen had examined herself several times afterward but failed to discover the Sparkfire Poison Plague. That did not mean it was nonexistent!
In fact, the Sparkfire Poison Plague was even more covert than the Bug Queen realized. Under Fan Lang's secret control, it silently infiltrated the three World-Destroying Martial Prowess and infected their internal cores.
The Bug Queen's three World-Destroying Martial Prowess shared one thing in common, which was also their greatest flaw: all three were living Zerg organisms, equivalent to an alternative form of Zerg life. Thus, they were restrained by the Sparkfire Poison Plague.
The first, Invincible Bug Disaster, was a massive aggregation of Zerg.
The second, the Thunder Severing Shattering Bomb, was a World-Destroying Martial Prowess created by humans. The Zerg had originally been unable to use it, but the Bug Queen exploited the Zerg's parasitic abilities, allowing them to infest its interior and alter its internal structure. Only then could it be used as an exception.
The third, the Ten Thousand Shadows Life Severing Thorn, was the same.
The Sparkfire Poison Plague had infected all three World-Destroying Martial Prowess and remained dormant until the Bug Queen launched her desperate counterattack and activated them. Only then did it take effect