Incenses are a gift of the Vegetable Kingdom of Mother Nature. There are resins (frankincense, myrrh, copal) plant parts like dried flowers (saffron) or leaves (sage, lavender, sweetgrass) , roots (ginger, high john, galbanum), barks (cinnamon, sandalwood, seeds (star anise) or juices (sugars). Sometimes essential oils are added as well some animal parts like powdered bull or buffalo horns, snake skins etc but more rarely.
Incenses or sacred mixtures are released in the air by flames. Fire activates their properties fueled by prayers, enhanced by the proven efficacy of an old recipe. Definitely they are useful and powerful tools in the arsenal of Hoodoo-Conjure-Rootwork.