Here's how it works: they stay in the shadows, good enhancements in Storehouse, waiting to use Holy Grail until after their opponent has discarded all their evil enhancements...and then, BAM, Saul turns into Paul, uses Built on a Rock, and activates Altar of Incense. Before you know it, three successful rescues, and then SoG and NJ to finish it off.
It took me a while to understand this strategy, but once I went against a few of these kinds of decks, I saw the geniousness (and pure evilness) of it.