Void wood was one of the toughest known, renewable substances in the universe. Depending on the exact variety of the tree, the toughness would be even greater, not to mention that the trees themselves have many amazing properties.
A Void Sequoia tree was by no means the strongest of such trees, but it definitely was one of the strongest. More importantly, it was absolutely massive in both height and width, making it a great option for a treehouse. The many space and void related properties of the tree itself also made it an excellent option.
Now that he had made the selection, Lex was faced with two more problems. The first was that he had to get his hands on a seed for the Void Sequoia tree, and secondly he had to learn how to rapidly nurture it. He was not referring to the ordinary means of nurturing, no. He meant the kind of nurturing that everyone thought was impossible, since he was in the business of doing impossible things anyway.