Hordak's Slime Troopers protect the Slime Pit from the Great Rebellion. They are also responsible for throwing captured prisoners into the Evil Horde Slime Pit. The Slime Troppers are immune to the slime from the pit.
When Hordak had two Horde Troopers steal the Book of Wisdom from Castle grayskull, He-Man traveled to Etheria to retrieve the Book with Rokkon & Stonedar. He-Man was over-powered by the Slime Troopers & thrown into the Slime Pit.