Draug is the highest ranking demon of war and the final boss of act 2 in Witcher 2: Assassins of Kings.
Draugs appear as spectre of millitary villains, arch-nemesis of war heroes. They are huge humanoid demons with fire magic and shapeshifting.
Draug appears as a literaly demonized and powered up wraith of Kaedveni general Vandergrift, who killed Seltirk of Gulet in duel. He didn't celebrate his victory long as Sabrina Glevisig summoned metheors that killed both armies and devastated battlefield. He was a ruthless military leader with extremally low tolerance of failures as he ordered to whip all scouts who failed him and to execute one third of them. When a soldier of Dun Banner asked him for military support of his ambushed brothers in arms, he refused saying that the Banner survived worse situations and has to survive this as well.
Draug faces Geralt of Rivia and dies in combat making one step closer to lift Sabrina's curse.
The Witcher 2: Assassin of Kings
The Witcher 3: Wild Hunt