King Crimson is a humanoid Stand of a height and build similar to Diavolo's, but tends to look much bigger and taller. Its body is covered by a raised diagonal grid, red underneath; save for its face, neck, shoulder guards, elbows, hands, abdomen, crotch, knees and feet/footwear. Its eyes comprise sharp orifices of a steep inward slant; from which emerge small, round fish-like/amphibian/reptilian eyes. It constantly bares its teeth through a small mouth. Its crown is flat; and from its forehead emerges a raised level that bears a smaller, oval face of the same expression. In earlier depictions, there were two raised levels.
Epitaph is the pink-colored second face on King Crimson's forehead, duplicated in its same position on either Doppio's forehead. It creates images on the inside of its user's hair, and as such whenever active, Doppio's bangs or Diavolo's hair is pulled forward and floats, allowing the user to look in.
Its design is inspired by the character George, from the 1990 science fiction film Total Recall, who had a second face on his chest.[3]
Abilities
Erasing Time: King Crimson's signature ability is to erase a given time frame lasting up to 10 seconds, starting from the instant the ability is activated.
"During" this erased time frame, most people carry on their activities unconsciously, and phenomenons like flying bullets continue normally. However, because the timeframe in which these actions would have happened is erased, the events do not exist per se and don't have lasting consequences. People won't remember anything that happened within the erased time nor will the phenomenons cause other events (as such flying bullets will appear to have passed through people without actually hurting them). When time appears again, people will suddenly find themselves in the situation they are supposed to be as if nothing unusual happened during the erased time frame.
On the other hand, Diavolo remains fully conscious during the erased time and only he can readjust his actions. Diavolo sees the erased time as a void filled with juxtapositions of what would have happened during this period in a fashion akin to Nude Descending a Staircase, allowing him to think out the next best action (for instance, when Bruno Bucciarati tried to punch Diavolo during the erased time, Diavolo saw Bruno's superimposed positions during his punch). While Diavolo can interact with himself (demonstrated when he cuts his own hand during the erased time) and can interact manually with objects not currently or fated to be affected by other phenomena (cleaning up his temporary work station at a motel within the erased time), it is worth noting that King Crimson cannot directly interact with people until time returns to normal, as opposed to The World, which was able to interact with the whole physical realm while it was stopped. What he sees are just projections of people, and not people themselves.
King Crimson's ability duration is dependent on Diavolo's stamina, as during the battle with Risotto Nero, he admitted that the iron-deficient and tired state he was currently in prevented him from erasing time for more than an instant; as such, he tries to make his fights short.
This ability can also be interpreted as "removing cause" in contrast to Gold Experience Requiem's ability to "remove effect". In the former's case, all interactions are skipped over and their results are nullified (events continue to occur for the people affected), whereas the latter instead creates a never-ending cycle of an interaction with no result ever occurring (a single event is never completed for the person affected). TL:DR It just works
Herculean Strength: King Crimson is a colossally powerful Stand able to punch through people's bodies or cleave them in a chop with significant ease. Unlike other melee-attacking Stands, it only uses single attacks that are almost always fatal rather than painful barrages. Examples include completely obliterating a fortune teller's upper body in a single punch and throwing a pairs of scissors with such strength that they completely severed Risotto Nero's right foot, among multiple other occasions where it effortlessly severed and rived body parts (especially limbs).
Prediction: From up to ten seconds, Epitaph gives Diavolo and Doppio the ability to see into the future by creating images on the inside of their bangs. The image produced includes the general area with Doppio/Diavolo as the main focus, allowing either of them to see what happens around them as well as directly at them. The prediction of the next ten seconds, according to Diavolo, cannot be avoided but can have steps taken to steer it in a new direction - such as when Doppio realized a pair of scissors would form inside his throat, he easily tore them out in order to save himself.
Doppio is the only one generally given Epitaph, but Diavolo is aware of how to use it and how long it lasts. It's unknown if Doppio can summon it himself or whether it's limited by Diavolo's permission. Doppio can also use King Crimson's arms as his own, primarily the right arm. The sub-Stand is entirely defense and reaction-based, and it can be assumed that it's how Diavolo uses it to predict how his opponents move and thus how to attack them accordingly. So far, only the ability of Gold Experience Requiem has been shown to bypass Epitaph and it does not seem to be affected by its user's stamina.
Much like DIO's "Time is frozen"/"And time resumes", Diavolo has his own phrases to go along with King Crimson's abilities: "Time has been erased" for when he activates the ability and "Time goes on again" for when he deactivates it.
All the JoJo video games that include Diavolo as a playable or in-game character have different interpretations on the power:
In Vento Aureo (PS2), the time erase was shown to slow down the opponent's actions while Diavolo still moves at normal speed for the duration of the obliterated time, a mechanism similar to Made in Heaven's time acceleration abilities.
In All-Star Battle, it acts similar to The World - through a number of abilities, Diavolo creates a erased time space (a special ability simply referred to as "Erasing Time") in which he is free to move about and the opponent is unable to take action. After a certain amount of time has passed, or as soon as Diavolo initiates an attack or ability, the spell is broken. King Crimson also acts as his dash and Epitaph can be activated to allow Diavolo automatic Stylish Dodging without depleting his Guard Gauge.
In Eyes of Heaven, Diavolo becomes invincible as well as invisible to his opponents within the erased time, causing him to gradually lose stamina. Other characters can still move. Furthermore, the Epitaph ability Diavolo had in All-Star Battle allowing him to dodge instantly after getting attacked returns in the form of a skill (assigned to the Square button).
The convoluted nature of King Crimson's abilities have become infamous among fans, with the phrase "it just works" often being used to facetiously handwave the long-standing lack of a clear and concise explanation.