For the off-season athlete there is no anabolic steroid more important or beneficial than testosterone. High levels of testosterone will promote significant increases in lean muscle mass and strength. This is assuming that the individual is consuming adequate calories. Compounds like Testosterone Propionate are not magical, you will still need to feed your body enough calories. During an off-season period of growth, this means total caloric intake will need to be slightly above maintenance. This will, unfortunately, promote body fat gain. However, the key to a successful off-season is gaining lean tissue while minimizing body fat gain to the fullest extent possible. By supplementing with Testosterone Propionate you will be able to achieve this more efficiently. High testosterone levels will promote a stronger metabolic rate. This is not a license to eat like there’s no end in sight, but you should be able to make better use of your calories.
Some bodybuilders and athletes use trenbolone esters for their muscle-building and otherwise performance-enhancing effects.  Such use is illegal in the United States and many other countries. The DEA classifies trenbolone and its esters as Schedule III controlled substances under the Controlled Substances Act .  Trenbolone is classified as a Schedule 4 drug in Canada  and a class C drug with no penalty for personal use or possession in the United Kingdom .  Use or possession of steroids without a prescription is a crime in Australia . 
THG, also known as 17α-ethyl-18-methyl-δ 9,11 -19-nortestosterone or as 17α-ethyl-18-methylestra-4,9,11-trien-17β-ol-3-one, is a synthetic estrane steroid and a 17α-alkylated derivative of nandrolone (19-nortestosterone). It is a modification of gestrinone (17α-ethynyl-18-methyl-19-nor-δ 9,11 -testosterone) in which the ethynyl group has been hydrogenated into an ethyl group , thereby converting the steroid from a norethisterone (17α-ethynyl-19-nortestosterone) derivative with weak AR activity into a norethandrolone (17α-ethyl-19-nortestosterone) derivative with powerful AR activity. THG is closely related to RU-2309 (the 17α-methyl variant), trenbolone (δ 9,11 -19-nortestosterone), metribolone (17α-methyl-δ 9,11 -19-nortestosterone), and norboletone (17α-ethyl-18-methyl-19-nortestosterone).