At the very least, he possesses the strength of an Invincible Saint King—and not just any Invincible Saint King. Emperor Wu and Emperor Proud are also known as Invincible Saint Kings by many Ghost Practitioners in the Netherworld, but he doesn't believe that their strength can compare to the present Blood Emperor!
An Invincible Saint King is only considered such in relation to many ordinary Peak Saint Kings; it doesn't necessarily mean they are genuinely invincible. As far as he knows, among the Nine Emperors, those ranked in the top few, such as the Tri-Eyed Emperor, Emperor Wu, and Emperor Proud, are all hailed as Invincible Saint Kings, yet their strength still varies.
If the Blood Emperor also possesses the strength of an Invincible Saint King, Frubor believes, he would surpass Emperor Wu, Emperor Proud, and even the Tri-Eyed Emperor, such Invincible Saint Kings.