"Within King Crimson's ability, time is erased from the world... and none can remember the tracks they left during this time! Clouds in the sky do not realize they have been scattered apart! The dying flame knows not of the moment it has been extinguished! All that remains is the results! It is only the results that remain in this world! Every action you take in a world where time is erased is futile! Only I alone can react to these actions! I can read every single one of your movements! This is the ability of my King Crimson!" "The Mystery of King Crimson, Part 3", Chapter 81
The main ability of King Crimson is it's ability to erase time. When the ability is activated, time itself is completely obliterated for up to 10 seconds, leaving a world where everyone subconsciously does what actions they were fated to perform subconsciously with zero knowledge of anything that happened during that time frame. However, Diavolo can move around independently, and cannot be interacted with at all while the ability is active, though the same applies to Diavolo being unable to interact with anything. During the ability, everyone's trajectory is forecasted seconds before happening, allowing Diavolo to know exactly what they'll do in a couple of seconds.
Gold Experience Requiem Part 1, Chapter 147.Diavolo's most common use of the ability is to position himself where he can easily deliver a killing blow, usually behind his opponent. And while he cannot interact with anything, if he has any wound that is causing bleeding, he can fling his own blood into the eyes of his victim, blinding them.
Inconsistencies
During the first ever encounter with the stand, Bruno Bucciarati personally transports his daughter to him, assuming that she'll be taken in by the father that she had never met. This all is immediately proven wrong when Bucciarati notices she is missing, and realizes he's holding her severed hand. While this scene helps bring tension and unease, it also is VERY confusing, because the only way Diavolo could have done that without being noticed is by erasing time... but he is not supposed to be able to interact with anything!
Later in that same encounter, Bucciarati follows him down into the crypt of the church they were in. After a brief scuffle, Bruno is faced against King Crimson's ability for the first time in which he sees his future self infront of him, completely overwhelming his mind and leaving him open for King Crimson to prepare a finishing strike. While cool, this ability of being able to see one's future self is never seen or explored again throughout the entire part.
Finally 2 instances where Diavolo yet again interacts with things while time was erased, specifically with taking his belongings and disappearing in one, and killing Narancia Ghirga in the other.