Terraria (Wiki): Blizzard Staff

The Blizzard Staff is a Hardmode, post-Plantera magic weapon that summons a storm of non-piercing icicles from the sky in exchange for mana rather than ammunition. It is the upgraded version of Meteor Staff with the exemption of projectiles that do not pierce nor explode.

The Blizzard Staff fires four projectiles per swing that travel in the cursor's direction. The icicles will move much further in any direction and can move horizontally due to the inability to move the cursor more than a few tiles away from the character (console). The projectiles that spawn within blocks pass through them, like the Star Veil and Starfury, but not as consistently. The player's screen advances a number of tiles when they open their inventory. While the screen is open, if the Player tap in the top center, they are tapping exactly where the icicles spawn, and the player will launch themselves in all directions. The player can fly off in any direction since it is attempting to get anywhere close to that point (within the accuracy margin of this weapon), which is completely encircling the icicles' spawn point. (mobile).

When used, the Blizzard Staff's velocity is reduced when passing through liquids. Although it becomes less obvious the lower the player aims the weapon, aiming lower increases this weapon's accuracy.

Combat-wise, the Blizzard Staff is less effective against smaller targets because its icicles cover a slightly larger area (console). 

The Blizzard Staff is best modified with Mythical for overall stats improvement.