Shadow Crystal

Behavior
Shadow Crystals appear during Eternal Darkness Event. They will cause permanent night on the island until one is destroyed. They will not attack the player, but Hollow Knights of Thunder and Hollow Knights of Fire will spawn for protection.

A definite place to find a Shadow Crystal is inside of a big, floating marble dome, however, they can also be found around the island. Destroying any one of the crystals will finish the event, but it will not remove other crystals.

Three Shadow Crystals are also protecting the Hollow King (Boss) which can not be attacked unless all of them are destroyed.

Drops

 * Astral Heart
 * Recipe for Blue Carpet Block