At some point after taking up residence on Cloud Mountain, Helmer claimed the maple for his own and turned it into the centerpiece of a training course. He surrounded it with dummies resembling wolves, and placed artificial birds in the branches, which were bare of leaves. The setup was designed to simulate a battle against multiple Lords of Prey and their wolf allies, with cords allowing the birds to swing through the air. The birds were equipped with blades, making the gauntlet a dangerous challenge for any soldier.
Helmer refused to allow anyone to intervene in his training, which nearly cost him his life shortly before the Attack on Cloud Mountain. After frightening off a mother and her young child who approached the maple, Helmer set his creations in motion. Set upon by numerous false birds, Helmer was almost killed, and only escaped due to the swift actions of Lord Rake, Wilfred Longtreader, and Smalden Joveson. Having recognized Smalls, Helmer was horrified at his endangerment of the heir to King Jupiter, but remained adamant about continuing his preparations for war.
Picket Longtreader later approached Helmer at the maple to ask for training as a soldier, but Helmer refused, prompting Picket to insult him. After being knocked down trying to escape a bird set loose by Helmer, Picket leaped at the older rabbit but was knocked back. Lord Rake, Emma, and Heather Longtreader then arrived on the scene, and Picket claimed that Helmer had been giving him some pointers. As the two does started to help Picket away, Helmer relented and initiated a calling ceremony, accepting Picket as his apprentice. Lord Rake reluctantly agreed to the arrangement under his own conditions, and Helmer instructed Picket to report for training the following day.
Picket did as ordered, and found Helmer reclining under the tree, a common position for the black rabbit who at times appeared to nap beneath its branches. The two soon launched into training, beginning with Helmer's instructions that "everything is a weapon" before going through a rigorous series of exercises. Despite Helmer's punishing methods, Picket greatly enjoyed the experience, and continued to visit the maple to receive Helmer's tutelage. Eventually, Helmer praised Picket's improvement, before discovering Picket's fear of heights after ordering him into the tree's branches.
Following the attack on Cloud Mountain, Picket and Helmer continued to train together beneath the tree. They were sitting under it by a fire one night when Captain Frye arrived with word of the supposed discovery of Picket's abducted family.
When soldiers from Halfwind Citadel arrived at Cloud Mountain for a Citadel Congress, several of them-including the Bracers-observed one of Helmer and Picket's training sessions beneath the tree. Engaged in sword practice, Helmer disarmed Picket, only to continue attacking him. Heather appeared and viewed the engagement with distaste, at which point Jo Shanks learned her identity.
The tree was later left abandoned after Helmer relocated to Halfwind to train the new Fowlers unit. Upon returning there just before the Battle of Rockback Valley, Heather observed a young buck playing beneath the tree, only to be carried off and scolded by his mother.