In-Saba Nur is a Quintesson executioner. Like most Quintessons, he thinks he's pretty damn clever.
Universe: Featuring the Wreckers
During the Quintessons' post-Great Reformatting invasion of Cybertron, In-Saba Nur and his Sharkticons and Allicons planned to take a great fortress on the cliffs overlooking a vast canyon. Those foolish Transformers had left the canyon unguarded -- a grave tactical error, to be sure. He had even ordered his fellow Quintesson, Vashik, to use his armies to draw troops away from the fortress. It would be a simple endeavor to crawl up into the fortress through a duct which emptied into the canyon. So very, very simple. What fools these Predacons were.
It was then that the duct unleashed torrents of molten magma, filling the canyon, and killing In-Saba Nur and all the troops under his command. Overlooking the canyon, Galvatron laughed at In-Saba Nur's stupidity. Chucking Vashik into the new magma river, he and Megastorm announced their intention to rebuild Darkmount, the fortress above, into a new Predacon capital.