The Ghost is one of (if not the) ultimate and ever present dangers in all Spelunky games, and in Spelunky 2 it is no exception. The ghost will appear after 3 minutes in a standard level. With the Four-leaf Clover equipped the time limit will be 5 minutes.
The Ghost always spawns in from the side if the screen closest to the player. Its arrival will be marked with the text "A terrible chill runs up your spine!" followed by the music changing pitch and slowing down.
It has similar behavior patterns in Spelunky 2 as it does the first 2 games, albeit with some key differences. Firstly, the ghost is about twice as fast as it is in Spelunky HD. By extension this much decreases the incentive to use ghost running as an effective technique, although the ghost is still capable of changing gems into diamonds. It has roughly the same sprites/animation as it does from HD, albeit with more detail and higher transparency. The ghost is also able to follow the player into sub rooms, but will disappear next level.
The most significant difference of the ghost in the game compared to the others is that after a certain amount of time it will split into 2 smaller ghosts. One of them shares the same unhappy expression as the normal ghost and moves at about the same speed. The second one has a smile and is faster. It will chase the player until it comes into close proximity to them. It will then proceed to rotate around the player, keeping a steady yet short distance away. When tracking the player, the smiling ghost has a small delay, so if you walk towards it you can kill yourself on it. It will never however touch you from its own movements. The presence of 2 smaller ghosts may also allow for some degree of different ghosting strategy. The 2 ghosts are even able to split again, with 4 smaller ghosts being possible.
Easter Eggs
As before, the ghost can be temporarily stunned by using the Camera on it, causing it to change appearance, pull a pose and stay stationary for a short period.
The Ghost after having her picture taken with the Camera
Theories
It is theorized by the Spelunky community that the Ghost in Spelunky 2 is actually that of The Empress, an otherwise unseen character in the game. This is due to the regalia of the Ghost in its true form closely matching that of a Chinese noble, similar to that which would match the aesthetics of Tide_Pool. In addition, Great Humphead's description mentions that the Empress hasn't returned to feed him in quite some time.