Pit Trap

{2}, {t}: tap target creature your oponent
controls with power 4 or less power.
{1}, {t}: when a creture a oponent controls
Attacks you can block with a 2/4 instead.
If Pit Trap is exiled or destroyed lose
3 life.
{4}, Sacrafice Pit Trap and deal damage
Equal to the number of times you blocked
with it.