Lerahk was the Rahkshi of Poison, meaning he is the dark spawn prince of toxic, and the dark spawn warrior of sickness, for almost all his enemies get sick before the battle could even start, alltough, only wrothy oppoents are amunne, it's powers won't effect allies (fellow rahkshi and other darkspawn warriors, the dark spawn lords and those aidding them or whoever is leading them for an exsample) and theres a change that the intinct sickness may be off depending on if he's powered by either rage or the presents of fellow Rahkshi. Its Kraata was lemon metallic/bright yellowish green. Although not a cunning planner, Lerahk more than made up for what he lacked in intelligence with sheer power. The tip of his staff could poison anything - plants, animals, soil, or any foe he might choose. Unlike Kurahk and Turahk, his power didn't work over a distance - the staff had to be in physical contact with the target.
Lerahk also succeeded in poisoning Tahu during the battle over the Mask of Light. This filled him with negative emotion and it began to kill him from the inside. He was later healed by the other Toa Nuva, but it severely weakened them, showing the power of Lerahk's poison.
Lerahk was chosen by Makuta Teridax to go after the Avohkii because its power was the enemy of purity: The prospect of Ga-Matoran. currently, Lerahk incredably become one of the vanguards of a new master, Emperor Fang, his evil presents similates the Makuta that he and the other rahkshis obey him without question (Rahkshis don't talk anyway) and now leads an army of non-dark spawnic Vaki.