So, as it turns out, the base Purery XYZs are Rank 2 Fairy Monsters.
Angel of Mischief is a Rank 4 Dark Fairy Monster.
Thus, if we have a way to make the base Purery XYZs Dark, we can use Rank-Up-Magic Astral Force to get ourselves up into them, with all the materials that Purery naturally stack on themselves.
And thus, in comes Lair of Darkness.
I will say again, this is probably a really bad idea. It's really funny though, so I made the deck.