There are many strange details in 2nd Kings 3, but the backstory is a rebellion of the ancient kingdom of Moab that roped in the northern and southern kingdoms of Israel and Edom to the southeast.
This chapter helps illustrate apostle Paul’s teaching that the “wages of sin is death” (Rom. 6:23). In this case, the wages of Moab’s rebellion was death.
In 1st Kings 22, we read about the final events that lead up to Ahab’s death. For those of us who are trying to walk a righteous life, the mistake and foibles of the unrighteous can still provide us powerful lessons, including the danger of making promises in haste and only listening to part of God’s instruction rather than all of it, but probably the most important lesson from this final chapter of Ahab’s life is that God does not need 400 voices to teach you His truth. He only needs one.