If you remember that this occurred some 20 years after the Invasion, you can understand how uppity this kingdom was when a portal opened up on their front yard, they thought it was another Phyrexian monstrosity.  It was Jasmine, the young and volatile princess of the kingdom, who charged head-first for the portal, with the need for payback for the loss of her fellow planeswalkers     especially her mentor, none other than the Great Artificer Ursa himself. 5. The Dominarian Books, Third Century AD It didn’t take Jasmine long to realize that this portal didn’t originate from Phyrexia at all, but at a thriving organic planet that nobody on Dominaria have ever seen, not even Ursa, not even the Theran. Her first thought would be to liberate this planet from the Phyrexians, but that seemed unlikely that would be the case, when she took stock at the mana of Earth, it wasn’t stable enough for no more than a few wizards o    r just one planeswalker     to fully live on.  Therefore, she thought up a Plan B:  Close the portal and protect it from those whose looking for a ripe planet to pick.  Here’s where the Dominarian books come in.  Jasmine had 20 of them sent through the portal.  One will be the actual door for the sealed portal, and the other 19 will provide the key.  Only when all 20 are gathered together will the portal reopen.  All she needed is a power source to provide the right amount of mana needed for the sealing, since it’s more than what the mana of Earth at that time could handle. Wonders of Wonders, what would Jasmine nearly slip her foot against than the marble that started all this, the Mirari. I don’t know how long she herself was tempted by it’s power, however.  I’d figure that she’d make a find queen deity for a whole planet if she wanted, even without the Smasher. She didn’t have enough time, however, because she got a good idea on what the Mirari does to people on this planet when she saw the Demon who made that portal. What she did next was a great sacrifice on her part.  She sealed the portal from Earth’s side, forever locking herself away from her home.  She battled with the Demon for the control of the Mirari, and got a hold of it for just enough time to cast the spell, sealing the portal with the 20 Dominarian books and scattering them to the farthest reaches of Earth, with the hope that they would never be gathered together.  But thanks to the Mirari, not only was the portal sealed, but also the Demon and Jasmine herself as well, for each of them ended up locked inside a book of their own.