Stardust Fragment

This pillar is where a summoner run finishes. The armor made from these is the only set that boosts every category of summon weapon at once, and its bonus adds a guardian that fights alongside you without eating a minion slot. There is no real competition for the class at that point in the game.

One clear of the pillar will not cover the full crafting list, so plan on several. Fragments convert between the four types, which means a surplus left over from another pillar can be turned into these rather than sitting in a chest forever. Anyone chasing the complete set should be hoarding all four colors, not just this one.

Twenty of each fragment builds a Celestial Sigil, which summons the Moon Lord directly with no pillars in between. Once you can beat him reliably that is the fastest Luminite farm available, and it turns leftover fragments into another attempt instead of dead inventory weight.