I believe the way Shiva's Third Eye works is that it persists to the next round if you clear the round without using a turn, so by using rippers.
I've been having luck with my Orochi zombie team in the mask dungeon.. the trick seems to be being able to eliminate the divine masks that attack on the same turn before they attack, I have Neptune for poison, Berserk for heart to water conversion, and Siren for hearts. Only died once out of three tries (due to a fluke, not even sure how I died since the perseverence triggered..)
Now I have a bunch of masks of every color and a Mystic Mask, though I have nothing to use them on as yet so they're just clogging box space. :T I'm trying to evolve my Vampire which requires 4x Violet Demon Masks.