Board Thread:General Discussion/@comment-1739368-20121205124732/@comment-27560171-20161021162606

The best explanation I've seen for KC is as follows:

Diavolo "Erases" time for everyone but himself. In the erased time, he can see what everybody else will do, and what will happen after the "Erased" time ends. While in "Erased" time, he is immune to attacks, and can move around, but the second he attacks, the erased time ends. Furthermore, everyone else will carry on with what they were doing before, but will not remember what they just did. In essence, Diavolo is immune to "fate" while in erased time.