There are so many things you can do with these kinds of things. I am using an ancient golden dragon for my campaign and I want to have a ghost follow my players around.

Where is it getting +5 to hit from for its Withering Touch? if its a dex attack, it should be +3, unless it is using its charisma?

Is the movement between the material and ethereal plane at will? It doesn't indicate needing to take an action or bonus action, but also doesn't limit it to once per turn or anything. As written couldn't the ghost jump to the material plane, attack, and retreat to the ethereal with no way for players to ever hit it unless they hold their action to attack?

Does leomund’s tiny hut stop these creatures?

can’t wait for one of my players to get possessed 

i wanna be a ghost

Quote from Bigbywolfe >>

Is the movement between the material and ethereal plane at will? It doesn't indicate needing to take an action or bonus action, but also doesn't limit it to once per turn or anything. As written couldn't the ghost jump to the material plane, attack, and retreat to the ethereal with no way for players to ever hit it unless they hold their action to attack?

 It is listed under "Actions", so I'm assuming it takes an Action.

spoopy

I'm thinking about using these ghosts as the main enemy of my campaign but with all those immunities i dont know if i hsould just make it a tough challenge or nerf the ghosts a bit. 

Quote from Radames >>

It says the challenge rating is 4.  That means that an appropriately equipped and well-rested party of four 4th-level adventurers should be able to defeat a ghost without suffering any casualties?  Therefore, this wouldn't be appropriate for a group of four or five 1st-level characters?

 It absolutely would be appropriate for 1st-level characters; if the players want to explore an ancient, cursed burial site, they should expect to find ghosts.

Think not based on what is "balanced", but on what makes sense for a given location, and make sure to telegraph this danger clearly.

If you only throw "balanced" combat encounters at PCs, the game lacks any sense of danger. This is also why you shouldn't base random encounter tables on the party's current level; it doesn't make sense for the world to magically alter itself based on the power level of the characters.

Question: if a barbarian is raging and is immune to being charmed, does that include being possessed?

I once made a world that was filled with the supernatural, and made an encounter with a ghost that haunted the house the party bought as a home-base. It was ridiculously fun, making the ghost out to be this horrible, dread-inducing creature and then it just shows up and engages in casual conversation about the place and its history. She showed the party to her corpse, locked in the basement and clearly tortured, and they buried it, putting her to rest... until she showed up the next time they came by and said that she was too attached to them to move on. She and all the other supernatural creatures the party put to rest ended up staying there as well. There was even a time where one of the PCs ended up dying (mostly of their own volition) and their spirit stayed in their home-base for the rest of the campaign. I was running like 4 different campaigns over the weekends so I ended up dropping that one, but I still wish that I chose a different one to drop instead, I really liked that campaign and it was refreshingly unique. 

"If the save fails by 5 or more, the target also ages 1d4 × 10 years"

CR 4 my ass. For a party under level 9 this is crippling a character if it's unlucky enough to be 4 on that 1d4.

Better have a greater restoration npc within 24 hours of them if they're not level 9.

is it weird that i had a ghost be the wife of a doppelganger?

According to the lore behind Doppelgangers, they aren't really capable of feeling "love," even being "too lazy or self-interested to raise their young," according to their Stat Block entry. However, it's a super fun idea, and using monsters in unique and abstract ways is a grade-A way to make any of your creations incredibly interesting.

I once had my players go through an encounter where a Ghost possessed a Werebear, and they eventually came to love each other, their souls fusing as a result of their bond, allowing both to have control over the body (dictated whenever certain moments happen and such). Having two people that love each other literally fuse body-and-soul was something I just thought was cool and threw at the wall in a random encounter, and my players loved it. 

Using Ghosts in interesting ways is always substantially more fun than just having them be insane or super powerful Undead that the party has to hack through. Overall, I give your idea a 9/10.

Please, dear God, DO NOT put this beast up against low-level party members, especially martial-heavy ones. Its damage is higher than it should be by quite a bit, its resistances effectively double its HP against melee, its Condition Immunities prevent almost every debuff that could be used to even out the fight, and it can just nope out of anything that challenges it with a single Action. Below like double what the CR recommends, this thing is going to absolutely crush your party members.

I'd recommend using Ghosts for political intrigue and RP rather than combat, regardless of its strength. It's way more fun that way, and it's so hard to run with appropriate strength that it'd be far less painful to just use a different Undead. Using Specters and Poltergeists for low-lvl Undead combat would be far more appropriate, and the Revenant is a lot more balanced for mid-to-high lvl Undead combat stuff. 

Can a ghost still Fly while possessing someone?  I can see a particularly unpleasant ghost wanting to possess someone, fly up to the ceiling then dispossess them... * splat *

It says that they use the body, but it doesn't say if they lose their own abilities.

this monster should have never been published.

ghost moment