The corpse that rushed at the Thunder Emperor was ferocious in its attacks. It left no room for the Thunder Emperor to move bout and each slash from its long claws was perfectly aimed at a critical point. This was just the beginning. When the Thunder Emperor saw a thick liquid leaking from the long claws. He looked closer and he realized that it was poison.
Not just any normal poison but the deadliest poison in the Human realm. It was the White Sage poison.
In short, these corpses were killing machines and they had no conscience to hold them back Once unleashed by their master, they did everything to kill their target.
The Thunder Emperor was fighting against a single corpse but the pressure he felt was enough to force him into focusing entirely on the corpse. A single mistake would mean his death.