Strength is really a misnomer for the magic of body morph. These people can tap the essence of the Immaterium to alter their own bodies. They can increase their strength, speed, agility, vision, hearing, hair color, eye color. The more advanced Strength Shapers can alter their own features to resemble other people, or even other creatures. Classic stories of mythological creatures were likely caused by a Strength Shaper getting a bit crazy in their morphing. Strength Shapers are also called Hulks, Morphs.
The drawback of Strength is the toll it takes on the body. To maintain the altered form, the Shaper must hold a constant stream of essence. The living body knows its original form, and wants to return to it. The Shaper thus must force her body into an unnatural state with the application of essence. This obviously has side effects both temporary and long term. While in the altered form, in exchange for improved physics abilities, the Shaper’s mental and emotional state is impaired. After releasing the magic, the Shaper will experience fatigue both physical and mental. In the long term, Strength Shapers who over abuse their power will suffer bodily damage when using their power, much like exposure to the Veil Scar.