No, don't mix your HCG with your test and mast. You can combine your test and mast. Thats no problem at all, but I wouldn't suggest combining these oils with your HCG. Not to mention, although HCG can be taken IM, it is normally done sub-q, with an insulin pin. It will be much harder to get an accurate measurement with your 3cc steroid barrel, than it would if you use a 1cc or .5cc insulin pin.