No steroid is a "shredder" and any steroid can support muscle acquisition. Some drugs like oxandrolone and stanozolol are significantly less androgenic than other drugs, which means somewhat higher doses may be required to gain lean body mass. A number of factors determine the potential effectiveness of a particular drug on a particular trainee, one of which is her AAS usage history. If you've never used any AAS before, then I absolutely guarantee you that, given the proper diet and training, even oxandrolone (anavar) would put muscle on you.