So based from what I saw in the trailer, Yukari's occult allows her to set up a crack that grows larger and can only be activated when the opponent makes contact with it. Her character profile states that it can be one of the possibilies:
"mysterious detritus, a dimensional rift, or even Yukari herself"
Her profile also implied that it's random, but is it really though? I mean there are only three outcomes, so there must be a sequence, just like Marisa's occult right?