The Crystal Cave is connected to the Duke's Archives, close to the last bonfire.
This area is difficult because of the fact that some of the walkways are invisible. The snowflakes falling from the ceiling and Orange Guidance Soapstone etched from other worlds can guide the player on these walkways. The player can also shoot arrows at the air, or drop Prism Stones to see if they stick. The enemies may prove to be an annoyance when on narrow crystal walkways. This makes it easy for the player to fall off with or without being hit.
Crystal Cave is perhaps the best location for farming Twinkling Titanite because it's a common drop from Giant Clam, especially with raised Item Discovery. It's recommended to kill Seath first, then the bonfire in the boss area will be unlocked, which is located just next to a cave with a group of Giant Clams for easy farming.
- The Lesser Butterflies in the area are initially passive and are aggro'd if the player attacks or gets very close to them. They will not land nor drop a special soul, unlike the Moonlight Butterfly boss.
- Getting Seath to destroy the Primorial Crystal will give the player a good opportunity to attack his tail for the Moonlight Greatsword.