Stardust Dragon Staff

To obtain this staff you must defeat the Pillars that are spawned on your Post-Golem world after you defeat Lunatic Cultist.

The Stardust Dragon Staff is unique in the sense that Extra Minion Spawns don't increase the number of minions that you spawn, but rather increases the Dragon's Size and Damage.

A screenshot of the 1-Minion Summon A Screenshot of the Dragon with 8 Extra Minions A video of it's Damage.