Tornado

Manipulating the great winds into a fearsome cyclone, the Druid sends this force of Destruction into a throng of opponents, crushing into them and leaving devastation in its wake.

The way to use

Tornado is to lay down a lot of them. The spell creates one medium-sized (size 3) projectile that moves in a non-random but erratic trajectory away from the caster for 3 seconds.

Tornado's projectile actually deals two different sets of damage, which can be described as "collision" damage and "periodic" damage. Collision damage can be blocked with a shield, but periodic damage cannot.

Any target that comes into contact with the projectile itself will take collision damage. Collision damage is subject to a 25 frame Next Hit Delay and utilizes the Last Collide mechanic, making any given target extremely unlikely to be damaged twice by the collision damage from a single casting of

Tornado.

Every 15 frames,

Tornado will deal periodic damage to any target within or adjacent to the projectile. Periodic damage is subject to neither Next Hit Delay nor Last Collide.

It's best to aim past a monster sort of like Barbarian's

Whirlwind rather than click on a monster and cast.

Once you have experience with

Tornado you can use it more effectively.