Fall of the Scalecrusher (1)
After closing his status window, Karsha retrieved the Book of Annihilation once more and quickly skimmed to the page where the tasks began. The book didn't show all the Overlords, only one at a time, so for Karsha to get the next information about the Overlords, he had to kill them in the order listed in the book.
The first on the list was ScaleCrusher, an Overlord known for its incredibly hard skin, scales, and everything covering it. It had the strongest defense among the Overlords, and Karsha would be facing it first. He was pleased because this was the same decision he would have made, with or without the Book of Annihilation.
After his near-death experience with that snake, he had planned to get stronger and kill that Overlord first before going after the rest. Killing ScaleCrusher would help him conquer some of his inner demons.