Blood Hunter's Detailed Ability Tooltip for Blood Crazy doesn't indicate how much damage is gained by the hero it is cast on.
"There is no teacher but the enemy. No one but the enemy will ever tell you what the enemy is going to do. No one but the enemy will ever teach you how to destroy and conquer. Only the enemy shows you where you are weak. Only the enemy tells you where he is strong. And the only rules of the game are what you can do to him and what you can stop him from doing to you."