Grave River enters the battlefield tapped.
: Add or to your mana pool.
Put Grave River on top of your library: Add to your mana pool.
, , Sacrifice Grave River: Target creature gets -2/-2 until end of turn.
: Add 
or 
to your mana pool.
to your mana pool. , , Sacrifice Grave River: Target creature gets -2/-2 until end of turn.
