Arachne Crystal

Arachne Crystals are used to summon the Stronger version of Arachne. They are obtained with talking to Shaggy after finding all Relics and Uber Relics and completing both quests while having 3 Arachne Fragments, 8 enchanted Spider Eyes and 30 Enchanted Strings in the inventory. This gets you 1 Arachne Crystal.