(: Add or to your mana pool.)
When Reef Bog enters the battlefield, return a land you control to its owner's hand.
: Reef Bog becomes a 2/1 blue and black Merfolk creature until end of turn. It's still a land.
: Add 
or 
to your mana pool.): Reef Bog becomes a 2/1 blue and black Merfolk creature until end of turn. It's still a land.
