(: Add or to your mana pool.)
Treetop River enters the battlefield tapped unless you sacrifice a Beast.
: Treetop River becomes a 1/1 green and blue Elf creature with flying until end of turn. It's still a land.
: Add 
or 
to your mana pool.)
: Treetop River becomes a 1/1 green and blue Elf creature with flying until end of turn. It's still a land.
