Warning: reader take caution. Really gross

But for a huge chunk of meat torn from his thigh and blood gurgling from the open arteries, fading to purple as it cascaded down his leg and coagulated in a pool around his foot, Gregory felt almost giddy. He looked around at the carnage; the landscape was a canvas of gore, the metallic stench of rendered flesh hung as a pall in the air. Strewn about were the remains of a hundred poor souls, torn asunder, ravaged and entangled. Gregory stumbled, nearly fell as a brief dagger of pain threw him forward, diminishing and gone as fast as it had come. The flow of blood began to weaken as the supply ran low. Gregory felt light headed, somehow euphoric as his brain starved. He lowered himself to the soaked earth, first kneeling, the maw of his wound gaping, then lying in grizzly repose, his head pillowed by a mutilated torso, nestled upon the soft belly, his face turned tilt against a ribcage. He slept. The blood from his ghastly cleavage had stopped. Gregory started awake in agony. He peered down at the source of his pain, now mottled black and red, bisected by a stained white stripe, bone. He turned in wretched shock and in doing so buried his face within the entrails of the quartered corpse beneath his head. He succumbed to his rising gorge and vomited the bile of an empty gut, afterward wincing at the burn at the back of his gullet. All the while, his leg continued to strangle his coherence, thudding and pulsing, unrelenting. The air began to thicken with the familiar bouquet of decomposition. His nostrils filled with air, acrid and bitter, an excremental exhale passed his parched lips, his breath more pungent than that of the bloated atrocity surrounding him. Gregory wished he had never come to his senses. Here, now, cognisance was a curse. His memory was as butchered as the men scattered about. As he lay, miserable, a strange thing happened. To begin with, he couldn't move. No foul air entered or exited his lungs, the searing pain from his leg was gone, he smelled......... Nothing. His vision faltered, in seconds he went blind. He heard his last heartbeat an instant before his brain shut off.     


PS: Please feel free to identify the major element missing from the story.