Where is this?

When it was over, there were only corpses that were lying on the ground.

The sharp arrows had filled the princes with holes and there was no way that they would survive with their bodies filled with holes like this.

A door opened up in the stone wall and there was someone that walked through this opening.

It was the fourth prince who was followed by two people holding staves in their hands.

These were magicians employed by the fourth prince and the one that had manipulated this cave. They were earth magicians that had sealed this place off and had created those openings for the arrows to come through.

As he stood over the corpses of his brothers, the fourth prince gave a sigh as he said, "If only you were willing to listen to our royal father instead of cozying up to those who flatter you to go against your own family, it wouldn't have ended like this."