Aqua Snake (3.5e Spell)

A vaguely snake-like wave rushes out, rolling along the surface of the ground and overrunning over all the kobolds!

You conjure a snake out of water made of six 5 ft cubes which must be contiguous, forming a "front" and "back". Creatures cause in its path take 1d6 bludgeoning damage and fall prone (max 20d6 at 20th), Reflex save to halve the damage and negate the prone effect. Creatures attempting to cross the squares inhabited by the snake are also subject to the effect. Each round you concentrate, the snake moves 30 feet though its squares must always remain contiguous. It cannot leave its surface and destroys itself if it leaves the spell area, runs into a wall, or runs into itself.

Every time the snake knocks a creature prone or kills a creature, it grows larger by 2 additional cubes and its speed increases by +10 feet. Its growth is potentially infinite, up to the point where it literally runs out of room in the spell area.

If cast underwater it is not limited to a surface and may travel up and down, significently expanding its options. It is also difficult to see, and so the DC rises by +2.