Dissolve the magnesium chloride flakes in the hot water.
Meanwhile, warm the avocado oil and emulsifying wax over low heat in a small saucepan.
Once the magnesium flakes are dissolved and the emulsifying wax is melted and combined with the avocado oil, add the water/magnesium mixture to the oil and give it a whisk.
Add the Nighty-Night essential oil blend and whisk once more.
Store in an air-tight container and rub on 1/4-1/2 tsp. at a time before bedtime.