One potential use I've been thinking about it would be the following: Get the shadow atrium from the shadow setpiece. Sail or fly (as Woodie) your way to lunar island. Grab yourself a message in a bottle and locate Hermit. Finish off the crab king and grab the Tribute. After that, head over once more to lunar island. Before placing the Tribute, toss in the Atrium (yes, you'll be able to interact with one of them celestial fissures) and finally socket in the celestial tribute. Doing so will cause a nightmare light to shine out of the celestial fissure for a brief moment, before emitting a lot of lune essence. After that, the following things will begin to happen:
You know the gestalts? Passive - Aggressive little things that float around you before eventually trying to induce more lunacy? Well, let me tell you that you've corrupted them. They no longer try to only put you asleep, but asleep for good. Each gestalt will appear slightly more molten, 0.25x bigger, and will deal 2.5 dmg each time they hit you (damage may vary, also, multiple hits in a short duration will multiply the damage factor by 2,75)
Remember the celestial fissures? No matter what kind of moon cycle it is, all of them will start spewing the maximum amount of lunar essence. There's also a 40% chance for a celestial fissure to actually explode in a slightly bigger crater (let's say as big as a cave hole, but instead of that weird shaped platform in the middle, there's just a gas type, blue-ish substance). When standing near one the player will receive up to +800 sanity/min over a radius of 6 tiles.
If you have/haven't built the Lunar Altar, it will shatter into pieces. (I wish I was able to actually make an animation of it cracking…)
Now all the things aside, let's speak about the lunar cycle: You see, now that you've corrupted a "lunar part" you just caused the blood moon to appear (take e.g from the Hamlet's Aporkalypse). That means: full time night time and increased overall difficulty
This will have an effect on the lunar island itself: The land will begin to tremble and crack, leaving one big part intact, while 3 other spear-shaped like bits will move outwards. In the middle there will be a round lunar formation: this is the place where the player will witness the being of the "celestial side". There will be a more glass looking version of the moon stone, with a structure similar to the ancient gateway laying next to it. The player will have to make haste and fix the broken celestial gateway (ran out of names) before the 9th night of the blood moon cycle [or the player will risk getting cast into moon rock]. The materials needed to fix the broken parts are: moon shards, moon rocks and a broken pearl <--- this will be the key. After repairing the parts, and reassembling the celestial gateway, an ominous and strange figure will appear: the celestial goddess (or celestial priestess or ancient light uh... whatever). She'll be the first character to have a harp for a voice, followed by a continuous silent whisper when in close proximity. The player's screen will begin to zoom in (just like in DS after freeing Maxwell or killing the Ancient Fuelweaver) The Celestial Goddess will give the player two options to choose from: either help her repair the broken altar (a different quest I will make a new discussion about once I've gathered enough ideas) or refuse to help her, thus beginning one last fight.
The Celestial Goddess has 3 special abilities: 1. She can occasionally parry a player's attacks (don't just go melee and hold the attack button, keep an eye on her wind-up animation). If she successfully parries the attack, it will stun the player and deal 10% the total damage of the attack. If she misses it, she'll be stunned for 4.08 seconds. 2. Each time whenever her HP drops by 25%, she'll emit illusions of herself. The player must attack the right one in order to get rid of the extra illusions, this can be found just by keeping an eye for leaking lunar essence or listening for an audio cue. If the player doesn't act quickly, they'll be stunned for 5 total seconds, allowing the true figure to actually attack the player. Her third ability will only be shown during a battlecry phase (high HP 0,72% - low HP 39.7%) or if her HP has been lowered below 30%. She'll pull out a lunar scepter, made of lunar glass, with an iridescent gem on the handle's end. She'll begin casting an arena made of moon crystals (not glass, a new type of structure), and receive a ranged attack. The player can do the following: telepoof (no matter the durabilty of the lazy explorer, as soon as you used it once, it will turn into a lunar rod, with 1 durability and ready to shatter) , deal 2500 damage in aprox: 3 - 4.2 min or shatter the wall with a nightmare sword (the wall is immune to other types of damage, and it also has 3000HP). If the player stands for too long in the arena, the screen will slowly start to get covered in moon glass. A timer (similar to the Gorge's hunger meter) will appear. The player has 6 min left to either kill the goddess, break the arena or will risk getting petrified in moon glass. Back to her stats: She has 20000 health, deals 190 dmg to the player and 250 to any mobs around her. (More mobs around her means more damage dealt by her. Each non player will increase her damage output by 60, so don't rely on them) The damage output will only change if there're more than 3 players in the fight (28 | 37 | 46 and so on). Once a battlecry phase begins, she'll gain a ranged attack. This will deal less damage than the melee attack, but therefore she'll swing faster than usual. [Melee Attack: 2 / 4 seconds | Ranged Attack: 4 - 6 / 3.53 - 4.21 seconds] [damage per ranged attack may vary from 90 - 124.2]
Drops: Lunar Lotus 120%, Glass Cutter 80%, Lunar Axe 60%, and 1 important item: the lunar staff: this staff will allow the player to do the following: manipulate waves (yes, you can now spawn waves on the sea to boost your boat's speed) call the light of the moon to protect you from Charlie and restore your sanity to 100% (has 30 uses) or channel all it's power to restore the lunar island and refresh the loot on it + unlock new recipes for the Celestial Tribute and the old crafting recipes from the lunar altar at a cost of 150 sanity and 70% total HP and a duration of a whole night. A new recipe would be a celestial sword made of the broken parts from the celestial altar (the parts can be found in the ocean, just like sunken treasures)
Now that you actually beat her, a ray of lunar light will start shining upon the repaired celestial gateway. The player must take action and leave that particular island before it will be ingulfed by light and start sinking . After 1 min, the player(s) screen will turn white, before being spawned elsewhere on the lunar island.
Keep in mind the following: the stuff the corruption changed on the lunar island will NOT be reversed unless the player helps the goddess repair the broken altar, Which is why I added two options for the player to choose. Also, I'm not a genius at giving balanced damage so don't get scared or amazed if you see some astrological numbers. Am open to any types of feedback / questions / suggestions
P.S - forgot to mention the Goddess's appearance. Remember the queen in the murals? or the metheus comic? Imagine that same face, but shaped similar to a gestalts head, white blue-ish - slightly transparent. She's as big as the Fuelweaver, is armored - chestplates made of lunar glass, some head gear (maybe a helmet) [will start appearing more damaged the longer the fight lasts and has a glowing aura around her]