Deca Durabolin, which is also known as Deca and Nandrolone decanoate, is one of the best performance enhancing drugs and anabolic steroids when it comes to stimulating endurance and muscle function gains.eca durabolin improves immune function. Deca Durabolin, which is also known as Deca and Nandrolone decanoate, is a popular anabolic steroid that is commonly recommended to provide dramatic relief to HIV/AIDS patients and use of this steroid is associated with immune system enhancements.