Forgotten Leylines of Man

If Forgotten Leylines of Man is in your opening hand, you may begin the game with it on the battlefield.
Whenever a Human creature dies, you may pay {w/b}{w/b}. If you do, target opponent loses X life and you gain X life where X is the number of
Human creature cards in your graveyard.
"The Nine have been forgotten. They truly are a race doomed to die." - Aenea, Elven Huntmistress