The tree grew taller and taller, rising above all the others. It became like a lookout tower, and it was tall enough to see far in all directions.
Erik shaped the branches so that they would not be too resistant to Thaids' weight. He didn't want to replicate the situation in the white desert, with flying thaids using the tree as a nesting place, which he had to then free, especially considering he wasn't strong enough to fight the beasts on equal ground.
To kill any kind of flying thaid here on Mur, Erik would need to kill them on the first strike, because if they spotted him, especially considering he didn't have clones, they would kill him.
He then created many hollow chambers within the gigantic trunk, connecting them to their underground shelter through hidden passages and stairs, and making the tree a natural tower.