Crown of Lucion is a Unique Helm in Diablo IV Season 15 for All classes. It drops from Astaroth.
Unique power
Each time you use a Skill with a Primary Resource Cost, gain [5 - 7.5]%[x] increased damage and Resource Cost is increased by 30%[+] for 6 seconds, stacking up to 6 times.
Affixes
Primary Core Stat
Resource Cost Reduction
Where it drops
Astaroth (Escalating Nightmare) - all-class boosted drop