First Folio

Let the Curtains Rise to Thunderous Applause. The theater Noble Phantasm of Caster of “Red,” Shakespeare. In the initial storyboarding, it had the power to rewind time, but since that didn't have much meaning in terms of the story's development, the idea was discarded. (The fact that a magician might make an appearance in a work after the prototype Fate/Apocrypha also played a big part in the decision.) Instead, what emerged was a graded-up version of “The Globe: Seat of the King.”
It is a Noble Phantasm that doesn't deal any physical damage, but it is the worst possible thing to face for certain Heroic Spirits. There basically aren't any heroes who don't have some kind of guilty conscience. Shakespeare can expose the traumas that everyone holds inside themselves, and by ridiculing or censuring them he can completely break their hearts.
The probability of being drowned and trapped within this Noble Phantasm is greater the more someone is confident of their physical strength. The only ones who can overcome this Noble Phantasm are those who can declare that they have not a single dirty stain on their lives. There are very few who can believe in something and have no regrets at all. If it's someone who can directly confront the trauma they hold, they might be able to somehow manage to overturn Shakespeare's piercing words, though—
When a Servant has had their heart broken by this Noble Phantasm, they receive the bad status of “absentmindedness.” In this state, they are completely defenseless, and as long as they don't have a Noble Phantasm which automatically responds to malice, they can't deal with any attack.
This Noble Phantasm originates from the “first” book that was published as a collection of Shakespeare's plays after his death. Therefore, Shakespeare himself did not directly participate in making it.

Fate/Apocrypha material: Fate/Apocrypha Encylopedia