Moondust is a resource tied to Selene, the Moon goddess. It is obtained from Selene-affiliated rooms, as a bonus when accepting her boons, and from Nightbloom reward chests. Equipping night-themed relics and praying to Selene at the hub increases per-run yield noticeably.

• Unlocking and upgrading Selene's boon tree at the Altar of Ashes (Moon skill enhancements that persist across runs)
• Strengthening Hex abilities tied to the Lunar Ray and other Moonlight Incantations
• Upgrading certain Moon-affinity relics and Arcana as a secondary material

Moondust is the dedicated fuel for Selene-oriented builds. Players not pursuing a Moonlight strategy will find limited use for it in early progression. Begin serious collection only after Arcana fundamentals and basic boon infrastructure are in place — at that point, Moondust investment pays off rapidly by elevating the entire Hex-based damage ceiling.