AmuletOfManyMinions/Crimson Cell Staff

The Crimson Cell Staff is a Pre-Hardmode staff that summons a circular, Crimson Altar-like entity to fight for you. The summoned cell will follow directly behind the player, releasing bursts of mini-Crimeras, similar to the Scourge of the Corruptor, as enemies come near. Summoning additional copies of this minion will increase the frequency with which it summons mini-Crimeras. After at least 4 copies have been summoned, the mini-Crimeras will have a chance to inflict the Ichor debuff. Like other minions, the summoned Crimson Cell is invincible and will last for an unlimited amount of time, unless the player dies, summons a replacement minion, or cancels the buff.

Its best modifier is Mythical for the widest array of set bonuses, or Ruthless for the highest damage output.