Just another way to separate the hunter from his money. Stick to hunting basics and the deer will come. You don't need bait or gimicks to kill deer.
mineral supplements have nothing to do with killing deer. it is about year round managing the deer. i have only seen a fawn once in many years come to a mineral lick in the fall and winter months. put it out in the spring ands replenish halfway through the summer. put your trail cameras on it if you want to get great pictures. as far as the rock goes ive never used one but you can get plain salt pretty cheap.