Anti-ghost combo?

[CursedRhubarb]

Looking through the spell lists while trying to decide what to grab/swap for my level up (we've survived to lvl 4 somehow) I came across the Earthbind spell and realized that it doesn't inflict any status, (paralyzed, grappled, whatnot) it simply reduces flying speed to 0 and the target falls if the strength save is failed.
Now, I'm curious since there are some things like ghosts and specters if I remember right that have a flying speed but zero normal movement. They are immune to things like charm or paralysis but since Earthbind doesn't add any status it should still hit and render them completely immobile since they wind up with 0 flying or normal movement.
So if I hit a ghost with Earthbind then next turn, or our wizard after I bind it, uses Mold Earth to plop a block of earth in the ghosts square or to bury it in a hole, would that kill the ghost eventually since it can't move and it would be stuck inside an object so it would take the damage each turn due to:

"Incorporeal Movement. The ghost can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object."

How would you rule it?

[Wondermndjr]

Ghosts can switch to the Ethereal Plane, so if you tried that the DM can just have it go to the Ethereal Plane while it is underground, wait for the spell to end, and then float up and return to the prime material. Also, this trick wouldn't work on a creature that hovers, like a beholder, since they will just keep floating in the air. By RAW it works, and at my table I'd let it work once as a reward for creativity. It is very limited in use though, only working on creatures with a flying speed as their only method of movement.

[CursedRhubarb]

I forgot the can switch planes, darn thought I found a good way to handle them at low levels.
Is there anything else to handle them at low level? It seems like they could just pop in, hit, then pop back out and be completely immune to ever being harmed until mid to high level PCs. I could be missing others but the only thing I can see on my list of spells (warlock) isn't until 13th level for my Mystic Arcanum 7th level spell. How would you normally handle something that can shift planes at will, especially low level?

[Wondermndjr]

The only way for a ghost to actually deal damage is Withering Touch, which is a melee attack. It has to switch planes as an action and can't affect you when it's in the Ethereal plane, so if it switches then you can't hurt it and it can't hurt you. If it decides to attack, then it leaves itself open for counterattack. For a CR 4 creature, its HP and AC are pretty low (45 and 11) and it doesn't resist force damage, so you can do solid damage with eldritch blast.

If you are looking for protection against them, protection from evil and good is on the warlock spell list. It gives undead disadvantage on attack rolls and you gain immunity to possession and fear. Knowing your exact party would make it easier to plan out a strategy, though.

Edit: Noticed that specters can't switch planes, so your earthbind + mold earth would work on them (theoretically). However they are CR 1 and pretty easy to defeat without expending one of your valuable spell slots, so it's probably not worth taking it just for them.

[CursedRhubarb]

I thought they could switch planes as part of their movement, much less worrysome if it's an action.