Emotional Control was a skill that combine very well with Rage and made someone get physically stronger at a fearsome level… It probably could make the skill also level up faster. Still, it was hard to imagine the user not getting exhausted from being angry.
With Transmutation, the user could turn everything into anything. It didn't even need a catalyst. The user could transform their mana into anything. It would just be a bit more costly.
With Avatar Creation, the user could use a medium to control that would have abilities similar to his. One could even use corpses or statues as an avatar… It was probably the closest thing Billy would find to a Shadow Clone.