Crafting requirements
Excalibur requires 3 Billion Cash, 30 Million Gems, and 100 Holy Grails. The Holy Grail grind is the longest step.
Sky Key farming
Sky Keys drop at 100% from Jotunheim open world mobs. Stock 3 keys per Floor 50 run, plus extras for Floor 41.
Holy Grail drop rates
Floor 41: 3.45% Holy Grail drop. Floor 50: 5.05% Holy Grail drop. Floor 50 is the most efficient farm.
Recommended team
Bring a Corrupted-trait Hashiromo or Yhwak, a Celestial-trait AOE (Yamamoto Secret), and one support. Do not engage the enrage shield without a cooldown reduction trait.
