Karavakos was a ruler of a petty township in a wilderness far north from the borders of the Nentir Valley. He was a tyrannical ruler who strove for the power of all the land around him but felt that his power was insufficient to control even his own lands let alone lands outside his own.
In search of more power he forged an alliance with a devil who gave him aid by giving him command of a legion of infernal soldiers, the only catch is that if he ever led the legion into defeeat he would be cast into eternal captivity (granted only an error by Karavakos could result in this because no army in the in this realm could kill an infernal soldier.)
Karavakos’s conquest continued as his army took over more and more land (in fact most of the world was under his control). With so much power he married the great eladrin princess Vyrellis who convinced him to expand his empire into the FeyWild (extending his rule across two dimensions of existence).
When Karavakos led his infernal army into the Feywild his army got slaughtered by the fey creatures since their demonic powers were useless in this realm. As result Karavakos was imprsoned in the Pyramid of Shadows along with his Eladrin bride Vyrellis.
In anger karavakos cut off the head of his bride and threw it into the charnel pit at the center of the pyramid.