By now, the ten King's Undead Cavalry had reached Stage 2, and they were incredibly powerful. However, the Skeletons they led were still quite weak.
Logically, if the King's Undead Cavalry were at Stage 2, the Skeletons that they led could grow to Stage 2 as well. However, let alone Stage 2, most weren't even at Stage 1. This was because all of the Stage 1 and above corpses were used to refine Blood God Pills, and very few were left to become Skeleton soldiers.
Moreover, each of the King's Undead Cavalrymen could control 3,000 Skeletons. In the early stages, 3,000 Skeletons was quite good, but now that Zhao Fu had an army of 160,000 people, 3,000 Skeletons didn't seem like much and couldn't help much anymore.
As such, Zhao Fu wondered what would happen if he fused the Disaster Fire with the King's Undead Cavalry.