The problem is that masteron is mostly a cosmetic steroid, and you will barely see any difference at such a high BF%. I always recommend to run masteron only if your BF% is below 12%. If you got more than that, it is just pointless. Instead, you could add Cardarine or SR9009 to the cycle – they are great for cutting, but they do not have side effects, so they will be an awesome addition to your cycle.