Cresselia
psychicCresselia can be summoned on Fullmoon Island, which can be found in Lukewarm Ocean biomes.
Locate Structure Command
/locate structure cobbleverse:fullmoon_islandHow to Obtain
First, we need to locate and defeat Elfio on Crescent Isle. He will drop the Member Card, which will greatly help in finding. Fullmoon Island. To find Crescent Isle, however, you will need the Mariner Logbook, which can only be found in shipwrecks. On finding one, put it in any regional cartography table with an empty map to find Crescent Isle.
Defeat Elfio and get the Member Card. Don't forget to loot the Lunar Wing from his bedside table before leaving.
Using the Member Card in any regional cartography table with an empty map will help you find Fullmoon Island.
Near the dock, you can see a tiny opening (left in the image, covered by vines). You will find a cute clearing. Nothing else is of note on the island so you can go straight to the house.
Our goal in this step is to find 8 dream string. If you'd like to find them yourself first, here is a hint as to where they are:
Dream String #1 (1st Floor). In a barrel underneath the plant in the north eastern most room.
Dream String #2 (2nd Floor). Underneath stair block in a closet.
Dream String #3 (2nd Floor). Top chest.
Dream String #4 (2nd Floor). Barrel behind the bottom right bunk bed.
Dream String #5 (2nd Floor). Behind the bookshelves in north western most room.
Dream String #6 (2nd Floor). Middle chest in south western most room.
Dream String #7 (3rd Floor). In barrel above the bed in north eastern most room.
Dream String #8 (4th Floor). You will need to climb these ladders behind the stairs that led up to the 3rd floor. It is in the left chest.
Now using the 8 Dream String and the Lunar Wing you got from the Crescent Isle, you can craft the Dream Catcher
Use the Dream Catcher on the Cresselia Altar. A Moonlight Amulet will drop from the altar, which is needed to spawn Darkrai
Cresselia will spawn downstairs, in the room with the statues that is also next to the bathroom.
