At the beginning of your upkeep, Rootwater Basin deals 1 damage to target creature you control.
: Add
to your mana pool. Activate this ability only if you control an Island.
: Add
to your mana pool. Activate this ability only if you control a Forest.

: Rootwater Basin becomes a 2/2 green and blue Crab creature with trample until end of turn. It's still a land.