For A Ghost to make an attack or when touch something they must build up energy, each turn they must roll a d20, must get a higher then a 10 for energy, they must get three successive rolls or 1 natural 20. The energy last the ghost 3 turns unless they rolled a Nat 20 which gives them energy for 5 turns. When they run out of energy, they must roll 3 more successive rolls. 

When The Ghost has Energy, They Gain a Physical Form. Which means they can take Damage. When a Ghost hits Zero Hit Points, They Die.

When a Ghost Hits Zero Hit Points, They Die.They Don’t get death saving throws since they’re already dead. when they die they don’t move on to the afterlife, but they just fade away and be forgotten forever…

Your ability scores each increase by 1.

Ghost are Ageless and can wonder the world for centuries

Humans vary widely in height and build, from barely 5 feet to well over 6 feet tall. Regardless of your position in that range, your size is Medium.

Your base walking speed is 30 feet.

You can speak, read, and write Common and one extra language of your choice. Humans typically learn the languages of other peoples they deal with, including obscure dialects. They are fond of sprinkling their speech with words borrowed from other tongues: Orc curses, Elvish musical expressions, Dwarvish military phrases, and so on.