Well, i havn't sheeted him up just yet, but my basic idea is that He was a Soviet Soldier, and at the end of world war two, whilst on a secret mission for the motherland, was betrayed by his superiors, who tested a vicious nerve gas on him. he dies, as do his fellow soldiers, with whom he had survived the war from the siege of Sevastopol to the end of the war, only to die here. but, much like the crow from the film of the same name, he is returned from death, albeit as a sort of revenant, He looks the same as he did on the day he died, Skin blackened and bruised all over, eyes hollow sockets, although now they bear ghostly flames, and he cannot rest until he has his revenge on all who betrayed him.
Basically his powers consist of immunity to bullets and stuff (chemical weapons, if a limbs cut off, so long as he can put the cut bits end to end they'll close back up, though that takes several hours for a wrist, and considerably longer the more vital the limb, up to a day or several for a sliced calf), since he's already dead. his weaknesses are that if his body were to be incinerated, or otherwise completely destroyed, he would, for all intents and purposes be dead.
His motivation for taking on Oswald is that his former commander, among others, defected to the Americans during the cold war, and has joined up with H.A.M.M.E.R in order to gain more power.
hence, Vladimir has in his mind at least, ample reason to burn H.A.M.M.E.R to the ground so that he can get to his target.
hows that sound?