Real 'dragon's blood' incense is made from the sap of certain species of trees. The original is from a very specific species, which is endangered, and only produces the aromatic deep red resin when the tree has a fatal infection by a specific fungus.
Inexpensive incenses will imitate this scent.
Its uses can be for courage, boldness, calling a loved one back, drawing money (don't so many claim to do this?), emotional intensity (yes, yet another other love spell list), and much more.
Dragons blood is used as a heavy duty clearing of negative energy that sage cant clear. There is also dragons blood soap available. I use it a lot to clear other people's "stuff" away since I tend to catch it easily, or for going into ritual to make sure you're not bringing baggage in.
Dragon's blood has a lot of uses because it acts as a focus and enhancer of will. It clears and purifies energy, kind of like clearing static from a radio signal. So whatever will you project becomes clearer and more potent.
Because of this the resin is useful as an incense to clear the air before a magical working, I recommend using an indirect heat burner (IE; a bowl or plate over a candle) as the resin likes to melt and then burn with heavy black smoke because as a sap it is mostly sugar. The indirect heat gives the same effect but with more steam than smoke. it also means the resin lasts longer before it becomes too hardened and black and needs replacing. I use a clay burner that was originally for scented wax and it works beautifully with a tea candle.
Dragon's blood can also be made into a really good ink that produces a fantastic shade of light blood-red. Or a darker red if you use it as incense for a while first. It is excellent for magical writing as it once again adds a lot of Oomph into your will as you write out your intent/magic and also releases the Dragon's blood as incense as the paper is burned.