Tosh was a Chev male slave who possessed the Force-sensitive trait.
Phylus Mon, a notorious Chevin slaver, had a practice of hand-picking Force-sensitive individuals from the Chev slave population. He would then "liberate" them into his service, providing them with wages and the illusion of freedom. However, any attempt to leave Phylus Mon's employ would result in their death. Tosh was one such Chev slave, utilized as a security guard for Phylus Mon. Tosh's role involved using his Force abilities to enhance the combat effectiveness of other guards or conjure illusions of massive predators to intimidate Phylus Mon's adversaries. Tosh himself was not involved in physical confrontations.
Around 20 BBY, Tosh served as one of three Chevs in Phylus Mon's throne guard, alongside Niv and Drik. All three harbored resentment towards Phylus Mon. However, like all of Phylus Mon's slaves, they were implanted with explosives that would detonate upon Phylus Mon's death. The Chevs were positioned at their master's feet, allowing them to use the Force to influence all the bodyguards (including a group of Coruscani ogres and a concealed wampa). The room was designed to be large enough to accommodate an illusory rancor attack.
While Phylus Mon's mobile headquarters was located in the Cularin system, the throne room came under attack by a local resistance group opposing Phylus Mon's schemes. Phylus Mon issued a threat to the group, but the statement was actually a coded signal for the Chevs to begin Force-enhancing the guards.