The Hulk bonded with the Venom symbiote takes on Dark Carnage, also known as Cletus Kasady, the original Carnage. It was all going well for Venom-Hulk but Dark Carnage stabbed him in the head with his tendrils and imparted his own view of the world to Venom-Hulk. This weakened him and allowed Dark Carnage to remove the Venom symbiote off the Hulk, and combined it to himself instead.
From – Absolute Carnage #4