It isn't mandatory to stack MassFX with Hyperdrol. We recommend it because (without getting too technical) both formulas play off each other. Think of it as an "anabolic alley oop". Stacking the two will cause a greater result than doubling up on one or the other. I am always very quick to recommend this stack because I know if you use it, there's a very good chance you'll want to come back for more.
I don't see much of an issue with inserting this with the AN stack. IGF-2 contains some ingredients which can increase growth hormone and testosterone levels and Neovar is a creatine-based product. Should not be any interactions, and MassFX should be able to play nicely into this stack.