I almost NEVER tell people to hold off on prohormones and I truly am not trying to be discouraging, but 6'0" 140 is quite thin -- and I have to agree with Russian. Phera is no beginner's PH either -- it's serious ****. Is your diet any good? Training program? Those are both crucial in making and retaining gains both on and off cycle.
I can't control what you do, so if you insist on a cycle, Torem is a suitable SERM. However, you should have an AI as well, as well as several other support supplements dosed at certain amounts. Most people take months researching before they commit to a cycle to optimize safety and maximize gains. I don't know your background and I know I sound like a douche, but it really is nothing to play around with. At your weight and height you have a TON of potential before you get into steroids, but again, your choice! We're just here offer advice to those who seek it.