Knowing Patchouli, she's probably summoning the Tome of the Night Sky, which in turn will require all 666 pages to be filled out, which in turn will then summon the Will of the Night Sky. But something goes horribly wrong in the summoning and the Will is turned into a corrupted program which can only kill every single living being on the planet. Turning the Will into the "Book of Darkness". And then Gensokyou will be consumed in a fiery magical nuclear planet killing Earth Shattering Kaboom within one hour of the summoning.
...Yeah...That's...how it got corrupted. A Wizard Did It!
Joking aside, very well done translucent magic swirls have created. It's always nice to see a good "mana" effect around a character, especially if it's a spell which seemingly requires a lot of mana. And multiple books. And bindings. Well done on the eyes too, making Patchy look very confident and well trained.