Battlefield Bleeder

At the beginning of your upkeep, sacrifice Battlefield Bleeder unless you lose a life. At of beginning of each attack step, you may lose a life. If you do, battlefield bleeder deals 1 damage to target creature your opponent controls and prevents 1 damage that would be dealt to target creature you control. When Battlefield Bleeder dies, each player loses X life, where X is equal to the number of creatures they control minus the number of creatures the player on their right control.