Kreig was the Witch King of Keld on Dominaria. He was the most powerful Keldon of all time; the product of Gatha's genetic splicing of Keldon and Phyrexian stock.
His power was great enough for the Phyrexians to take notice and attack Keld. He led his nation in numerous battles against the invaders; in one battle he encountered the Phyrexian Inner Circle member, Croag. Kreig wounded him but could not defeat him. He and Gatha jumped off a cliff, committing suicide so as not to fall into the hands of the Phyrexians.