Wizard Tip: Use Blizzard to compare items or skill changes without randomness.

Most Wizard spells respect the random nature of weapon damage, so if a weapon does 100-200 damage per hit, your magic missile or meteor will do 1000-2000 per cast. This can make it very difficult to see how much difference an item makes in the 'real world' - a weapon that does 80-2400 damage per hit will do 800-2400 per meteor, and you will need to track a lot of casts before you can see what is what.

The ticks from Blizzard are not random - they are a fixed amount based on (I assume) the average damage of the weapon. This means that you'll see a simple, repeatable change between different weapons. Using the examples above, Blizzard will tick for 150 with one weapon and 160 with the other.

This is also useful for testing other changes to your character (like people were doing with Magic Weapon being bugged, or if you want to see how much you'll gain for swapping in sparkflint over magic weapon).

tl;dr: Blizzard ignores randomness in weapon damage making it a perfect test spell for evaluating damage output.