I had an idea that all Planeswalkers have a pocket dimension called their "Library." :nat
When a planeswalker encounters a creature, person, or place, the story is recorded in a book in the planeswalker's Library.
Planeswalkers carry a book inclueding 60 of these "encounters" so that they can summon a copy of the things that they have seen or done.
for example;
Lets say that a planeswalker witnesses a battle between The Rakos and the Boros. There are Griffins. The planeswalker nocties the Griffins. They are recorded in the book in the library.