When Blackcleave Seafloor enters the battlefield, return a land you control to its owner's hand.
: Add or to your mana pool.
: Add to your mana pool. Put Blackcleave Seafloor on top of your library.
: Return Blackcleave Seafloor to its owner's hand.
: Add 
or 
to your mana pool.: Add 
to your mana pool. Put Blackcleave Seafloor on top of your library.: Return Blackcleave Seafloor to its owner's hand.
