In the Chronicles, my "world tree" is Drasil. The tree came down the worm hole when the fallen creator, Orbenos....renamed the Shadowling, came to Medelia. The idea for the tree came from Norse. So here goes.
In Norse mythology, the tree was called Yggdrasil. It grew in the middle of Asgard ( the home of the gods.) By all accounts, it was an "eternal green Ash tree." It's branches stretched over the nine worlds. The tree had three main roots. The first was in Asgard in what was called Urd's well. The second went down to the land of the giants, Jotunhein into Minir's well. The third went to Niflheim where it was believed the dragon Nidhug gnawed on the roots. On top of the tree, there was an eagle and the bottom was Nidhug the dragon. A squirrel, Ratatusk, went back and forth spreading gossip and keeping the eagle and the dragon constantly "disliking" each other.
In the Chronicles, I introduce Drasil. In the first part of Book One, the Shadowling wants to return to the Heart of Heavens and knows that the only way up to his former home is by climbing back up Drasil. He must have the laws in his possession to do so. Also, when his first came to Medelia, the magic tree was the place of entry to his new home, Medelia. I will have fun with Drasil in Book Two and in latter books.