Eu fiz uma extensa pesquisa sobre material na Árvore do Mundo e só encontrei uma pequena amostra de informação.
Adventurer's Vault e AV2 têm alguns itens "da árvore do mundo", mas nenhuma informação suplementar.
O Poder Primordial, o livro no qual o destino épico do World Tree Guardian foi publicado, tem isto a dizer:
The World Tree
The most ancient primal spirit of the forest, the World Tree is closely associated with Tree Father, but they are not the same spirit. The roots of the World Tree extend to the foundation of the earth, circulating life and primal power throughout the world. In fact, some shamans say that the World Tree is the spirit of the world itself--not any particular aspect of it, but the entire creation, its interconnected inhabitants and precariously balanced environments.
Some say that Corellon planted the World Tree and in that way seeded all the forests of the primeval world. Other legends say that Corellon or Tree Father, or the god and the spirit working together, gathered seeds from the World Tree and spread them across the world to plant the first forests.
Only characters who adopt the World Tree Guardian epic destiny in this book can call on the might of this ancient and powerful spirit, as they strive to protect it--and the world itself-- from destruction and corruption.
Eu pesquisei provavelmente em 90% dos livros 4e publicados e em quantas revistas eu pude, e esta é a única informação disponível.