: Water Servant gets +1/-1 until end of turn. : Water Servant gets -1/+1 until end of turn.
"This creature has innate perceptiveness. It knows when to rise and when to vanish into the tides."—Jestus Dreya, Of Elements and Eternity
Official Rulings for Water Servant
8/15/2010 : You can activate Water Servant's second ability even if doing so would cause Water Servant's power to be less than 0. If Water Servant's power is less than 0, treat it as 0 for all purposes except for further modifying it, or causing the power of another creature (such as Riptide Mangler) to become equal to it.