The Blizzard Staff is a weapon dropped by the Ice Queen during the Frost Moon. It showers the area in which the mouse is pointed with icicles, which have a small homing range. This weapon can be useful for dealing with event mobs like in a Pirate Invasion.
The weapon acts like an advanced version of how Starfury works before 1.2.
While the Blizzard Staff's use time states that it can be used every 10 frames, the icicles will actually fire every 5 frames (scaled by prefixes).
The icicles rained down can only travel through a small amount of blocks if they spawn inside them, otherwise they will break upon impact with blocks. This severely lowers effectiveness in enclosed areas.
The tooltip previously had a slight typo, saying that it rains "icycles", not icicles. This has since been fixed.