Say no to PH at your age!!!
But since you mentioned Mass FX... it's not a prohormone, and I don't know why people seem to keep mistaking it for one! It is hormonal and does mess a bit with your testosterone levels, but isn't harmful enough that you're going to stop growing taller, have a heart attack, and your nads will fall off and you'll never have kids!!!
Here's the scoop: At your age, your body is still maturing on a hormonal level. As you reach that sweet spot somewhere between 21 and perhaps 25 (?), your body chemistry will level off. When that happens, you can begin to play with it and experiment a little more. Until that time, PH are not an option you can look at and be respected over by much of this board. MFX will affect your body chemistry, but NOT in a way that you'll need to do any kind of post cycle therapy. It is an herbal product, like tribulus and many other test boosting products. I believe that if you wanted to do some MFX, you'd be ok with it. Though,IMO, I'd still be leary about it at your age.
Right now, you're "in your prime" and have stuff running through you that many of us only wish we still had! Train hard, keep your diet clean and high in protein, and you'll make gains. If you're looking to supplement, the basics are good - multivitamin, creatine, whey. From there, move up to BCAAs, Fish Oil, and maybe a pre-w/o stim.
You're right in doing your research. And you are doing it the right way by asking questions, despite how others may respond to you. Best of luck, my young friend. If you need help, that's what we're here to do.