Stardust is a surface-route resource found at Charon's shop, constellation rooms, and select trial reward chests in Erebus and the upper surface layers. Per-run yields are modest, giving it a rare feel compared to Bones or Shadow. Equipping certain constellation-linked Arcana and relics adds a meaningful collection bonus and makes dedicated Stardust runs viable.

• Crafting large-scale permanent upgrades via the Cauldron's Incantation system (higher-tier recipes require increasing amounts)
• Unlocking upper-tier Arcana Cards in constellation and surface-aligned categories
• Serving as a secondary cost alongside other materials in select hub upgrade menus

Stardust is the surface-route counterpart to Shadow — together they represent the two main tracks of permanent progression. Players who concentrate exclusively on Underworld runs will bottle-neck their Cauldron progress as higher Incantation recipes demand more Stardust. Rotating surface runs into the schedule regularly prevents this stall. When Stardust feels scarce, assembling a dedicated collection build with relevant relics and Arcana resolves the shortage efficiently.