From Worms Knowledge Base
Select this weapon, and your worm brings out a familiar looking meteorological device, spinning calmly with the wind. Click somewhere on the terrain and the device picks up speed, as a nasty-looking tornado begins to form over the selected region. The furious funnel reaches down until it touches the terrain at which point it begins to whip up worms, barrels, crates and mines this way and that, throwing them across the terrain, and tears up a layer of the ground like it were a carpet. The tornado moves across the terrain with the wind, until it eventually hits water, where it begins to disappear. It leaves behind it a trail of destruction, worms recovering on a shattered surface. The only safe place to hide is underground.
The game need no more than draw a vertical line from sky to the surface, and plaster an animation of a tornado on top. As the line moves in the direction of the wind and encounters terrain of differing heights, so the animation resizes itself to navigate the landscape. Objects too close to the line are thrust upward, in a zig-zag pattern, until eventually being thrown out left or right.
As the line moves over the land, the top layer of terrain is deleted, under cover of the destructive-looking animation. When the tornado meets water, it slowly fades away.
Most click & watch weapons are seen as easy ways to deliver mass destruction with minimal skill, but the Tornado is somewhat restricted in the damage it can do. Only worms on the surface are prone to its power, and the terrain deformation is limited to a thin strip of land. This makes the Tornado a great darkside weapons - allowing burrowing worms to attack lightsiders with ease, without putting themselves, or the land that protects them, at risk.
Like the Lightning Strike, Worms needs this weapon. The power of the weather has gone unharnessed throughout the Worms series and it's about time it made a dramatic appearance.