Devrar . . Before Teridax seized control of the Brotherhood of Makuta, Makuta Kompas design three Toa by tinkering with some Matoran to make them larger and stronger. Thus a Po-Matoran named Kakami, a Ta-Matoran named Badul, and a Ko-Matoran named Devrar were transformed into Kakami, Toa of Speed; Badul, Toa of Probability; and Devrar, Toa of Ice. As you can the, the elements were not transferred quite right, but these were the first Toa to be created from Matoran, so you can't really blame Kompas too much.
These Toa trained hard with Makuta Kompas for many years. Early on, in a training accident, Devrar's powers were siphoned out. Devrar did not give up, using his speed, strength, Kanohi, sword and claws he became a Toa to rival his brothers.
The three Toa and Kompas were eventually sent to Xia to protect it against a Zyglak attack. The Toa and Kompas prevailed and trapped the Zyglak, and Kompas, using his Olmak sent them into a pocket Dimension called Bythe. By extreme misfortune, Devrar was sucked into the portal with the Zyglak. Bythe was a fiery, volanic world and when the Zyglak arrived they were incinerated by a volanic eruption.
Devrar lept into the closing Olmak portal, but due to the portal's closing Devrar came out in an alternate universe, where several Toa had become powerful oppressors, and ruled harshly over the Matoran. All who had opposed them had been destroyed, the Makuta, several Toa, and brave Matoran. Horrified, Devrar went into hiding in a small cave on Xia, where he met a small group of Matoran who were planning a rebellion against their Toa oppressors. Devrar was quick to join the group, and eager to help in any way.
Meanwhile, Kompas, Kakami, and Badul re-opened the portal to Bythe and entered. They found that Devrar had mysteriously disappeared. They searched Bythe, and eventually gave up hope. The Toa and Kompas assumed Devrar was incinerated by the flames and poisonous fumes. They returned to there home universe and went back to Destral to mourn the loss of their friend