I would not try wax in this case because resin won’t adhere to wax. I worry that your resin may not completely cure and/or stay in one piece. It’s also going to be hard for the drip to keep looking like a drip, as it will want to change shape in the resin. (They usually try to go flat.)
If you want a drip effect that won’t color the resin, then your best bet is to cast drips separately, then include them in your clear resin castings later. Otherwise, you could try something like alcohol inks (nice drip, but will move, creating a ‘smoke effect’) or something thicker like paint. You will need to push the drip through the resin with something like a toothpick. Do it as little as necessary as to avoid mixing the color with the resin.