The first step to getting water to flow uphill, is enticing ice to melt backwards.

The Ice Tower is a damage absorber. Set it between a valuable unit and hostile fire. The attacking unit will retarget to attack the Ice Tower.

As a damage absorber, the Ice Tower is relatively weak, but it regenerates by itself if destroyed.

If built on a floating island, an Offensive Spell can destroy its island and kill the Ice Tower permanently.