Darkstone

Darkstones are created from four darkstone shards, which can be found along the eastern beaches of Devil's Island. The four shards are then combined by a NPC on Ash Island, past the campfire path.

Once created, a darkstone has the power to open the pentagram in the Dark Temple to a high level Darshak area, and to reanimate fallen bodies, similar to the effect during the Feast of Tsirrin.

"I'm pretty comfortable saying this because it's not really a secret, just poorly publicized - Wangah has no control over who does or doesn't get a darkstone. There's an NPC past the campfire path on west Ash that will trade four different shards for a full stone." — Largo