The Stardust Dragon Staff is a summoner weapon that summons a Stardust Dragon, which increases in size and damage each time it is cast, but the player must be able to summon more than one minion for this to take effect. (Casting the Staff twice will count as two minions, and so on.) It's extremely effective and will tear apart most mobs and bosses with ease.
The Stardust Dragon Staff can be crafted from Stardust Fragments which drop from the Stardust Pillar. The Stardust Dragon moves extremely fast, and also moves through blocks. The Dragon also has a longer range than most minions, which means that it will detect mobs before most of your other summons.