Incense of some kind. During the set in Chicago, John said something about gathering stuff for incense when he goes out into nature, so I imagine it's incense he's made himself.
Damn, I wish I knew what specifically. It smelled extremely good.
Great show, I hope they make new material again quickly. Their live show was fantastic (tho could have done without the openers). Anyone find Agalloch too loud live, though?