Tbol is both anabolic and androgenic in nature but its androgenic properties are mild at best...like Halo, although a very different steroid, it is extremely androgenic yet shows little to no androgenic effects. Further, yes, Tbol will shut down your natural testosterone production, taking it alone is not the best idea in the world; no testosterone is a lot worse than a little thinning of the hairline.
Side note, after reading this thread it seems some do not understand the difference between lean tissue gain and weight gain. 5-6lbs of actual muscle tissue is nothing to scoff at. Further, no one on earth and I don't care how genetically gifted they are is going to gain 15-20lbs of lean tissue on a Tbol cycle, anyone who claims they did is either lying or has absolutely no idea what they're talking about. A 15-20lb gain of actual lean tissue is enormous and would take a lot of hormones for an extended period of time to achieve in a permanent sense.