A whole lot of stuff! good gracious! protection is my first thought...wiping away evil intent and maybe sending it back? I got the impression that this thread would have to do with the multiple uses incense has - from pagan to Protestant to Catholic. As having personal knowledge of the Christians (but not Catholic, which Catholic use incense a LOT!) I can tell you they would deny deny deny that there is any "magical" purpose or power to be had and used from incense. Also one can find mainstream religious situations where incense would(is to) be used on a regular basis. Note: Of course, that would just be one of the (many) places and ways I would differ from mainstream Protestanism.
I think dragons blood can be used for many things. I personally use dragons blood every night before bed to help me feel more relaxed so that i can write before bed. I also have heard that you can use dragons blood like LynnBrown said before. To ward off evil spirits or negative energy in general.