Arnold got the temporary charge of the team after some protest from Sonya and her team. But with Arnold's summons surrounding them, they did not have much choice but to accept his conditions. They still had no idea how were they going to uproot the tree. So, Arnold's first phase of testing commenced.
He told them all to attack the tree one after another to see if something happens. He was hoping Nicole's ability would work, but sadly that wasn't the case. She could only make a dent where Arnold had shot the tree.