Abel's contract with the oak tree was a little like the one he had with Black Wind and White Cloud. Although you could not physically see it, it could be felt through the soul chain. The only difference was that White Cloud and Black Wind connected with Abel through the soul chain of his main soul, while the Oaktree connected with him through the ones of his druid soul.
Although his druid soul had now become an actual Druid, it didn't really increase his current fighting ability by much. It only opened up more potential for him to grow in the future.
After he returned to the Rogue encampment, he could still faintly see the giant oak tree from afar. He was not sure if it was a good idea to plant the oak tree there after all. Abel shook his head as he called Black Wind to the Stoney field through a small scale teleportation circle.