Younight, what are some cool combinations have you experimented with?
I must admit, that I've not tried anything too 'out-there'. Also, because I only have one heater, it's usually a combination of something on the heater, and a stick of something burning in the background.
I've done blends of things (all heated in the same dish, at the same time), but that's more parallel to a mukhallat than it is layering multiple oils on the skin, on-the-fly.
With 'layering' of incense, I sort-of think of it as similar to the recordings that've been made with multiple musicians, but using only one microphone, when the musicians are recorded 'live' (i.e. playing together, in the same room)... the challenge is to position the different instruments/vocals at different distances from the microphone to get a balanced mix. Guitars will be louder than vocals, but not as loud as drums, etc.
Because the smoky component of the ignited stick is almost always something I want in the background, my heater is usually (much) closer to me than the burning incense is.
I also don't bother 'layering' with sticks that are inherently complex with many different ingredients. Keeping each individual 'voice' simple (or as purely one-scent as possible) is what interests me.
Anyway. I've enjoyed hovering directly above some pure, white ambergris on my heater, with an aloeswood stick burning in the background.
Also; hovering above sandalwood on the heater and a stick of lavender incense (which I bought in Japan) in the background.
Crushed green Omani frankincense on the heater (5 or 6 feet away from me) with a stick of Kunmeido's Hosen (florals) burning in the background.
Palo Santo chips on the heater (a few feet away), and a stick of... actually, I don't even know what the incense is; he label contains only kanji (which I can't read), but it's floral.
...and a few others.
I'd been thinking what I'd like to layer with heating agarwood chips, and it came to me last week. I pass under a cherry tree while I walk through my neighborhood. The last couple of weeks, its blossoms (in full bloom!) have been putting-out an aroma that's got me smitten! I can imagine it being a fantastic mate with agarwood. Not sure if I can find an incense that actually captures that beautiful essence of sakura, but it's worth a try!
Here's the tree that I pass under:
Having said all of that... at the moment, I have a crushed stick of Tibetan Medical College's "Holy Land" on my heater. Plenty complex (and wonderful) on its own. No layering with this one!