The Ghost (Name can change if needed) is a unique troop that I think should be unlocked at Dark Barracks level 2. I think Hog Riders are a little too good for Lvl 2 Dark barracks but maybe thats just me. Anyway here are the ghosts stats:
Level 1
Damage per second: 28
Hitpoints: 42
Training Cost: 55 Dark Elixir
Favorite Target: Any
Damage Type: Single Target
Housing Space: 10
Training Time: 3m
Movement Speed: 15
Heres the unique part, The ghost is an AIR troop who flies fairly slow does a decent amount of damage and not too many hitpoints. The thing with the ghost is that SPLASH defenses, Heroes and Clan castle troops will not detect the ghost and it will simply fly right by. But Single Target defenses will detect the ghost and try to kill it as it would to any other troop.
The housing space should be fairly high to avoid people from using 100 ghosts or so. With FULLY maxed out army camps you would only be able to train 24 ghosts.
Defenses that detect ghost: Archer Tower, Hidden Tesla, Air Defense, Seeking Air Mine , X-bow, and Inferno Tower.
Defenses that WONT detect ghost: Wizard Tower, Air Bomb, Archer Queen and Clan Castle Troops.
And obviously Cannons, Mortars, Bombs, etc. wont detect the ghost since its an air unit.
As for upgrading, I think the max level ghost should be 4. And with each level up it gains anywhere from 5 to 15 damage per second, around 10 hitpoints, and about 8 more DE to the training Cost.
Appearance
The ghost will be a stereotypical faded whitish/greyish flying creature just like any other ghost. And im thinking level 1 and 2 ghosts should look the same but level 3 and 4 should have a greenish tint.
FEEDBACK IS GREATLY APPRECIATED THANKS:)
