This is Toa Czarkor. Once, a Toa of Magnetism. Now a giant, monstrous, power-hungry tyrant
He wields an Electromagnetic Whip, and wears the Mask of Metamorphosis, which allows the user to temporarily make any being either develop quickly or backwards in evolution (can theoretically turn a man into a monkey).
When he was just an ordinary Toa, he was part of a specialized Toa team who were tasked to protect the Av-Matoran on Karda Nui from Energy Storms shortly after the Toa Mata were put into status. However, during an intense Energy Storm, he got struck by a bolt of energy, thus causing Toa Czarkor to lose control of his elemental and mask powers.
His over-charged magnetic powers lead to the Av-Matoran's armor being viciously ripped from their bodies and re-attatched to Toa Czarkor's own body, and using his Mask of Metamorphosis, he grew to an immense size in order to accommodate the increased amount of armor.
Now infused with new-found strength and power, Toa Czarkor quickly developed an insatiable urge to absorb more energy, and found himself using his magnetic powers to rip the mechanical components off more innocent Av-Matoran to satiate his hunger. However, he was stopped by the combined forces of the few surviving Av-Matoran, and was blasted to bits.
His dismembered parts were then transported to Metru Nui, were Matoran would be able to study him. However, Toa Czarkor's soul was still contained within his mask, and he tried to kill the Matoran scientists who dared to approach his dismembered parts.
Out of fear, the Matoran transported his dismembered parts to an isolated cave, where he currently lays, waiting for someone careless enough to stumble upon him...
The red arrow points at a "lever" that can be pushed down to flip his shoulder'-mounted cannon upwards for manual usage.
Red arrows specify which parts will move and at what direction they will move
^ Toa Czarkor vs an Av-Matoran
^ Toa Czarkor alongside his "withered version"
Feedback, criticism, and improvements are always appreciated