Hollow Sycamore. Got hit by lightning a couple years ago. It smoldered for about four days. I wish oak stumps were this easy.
I've had multiple stumps give me a headache. Currently trying to get rid of some type of pine. I used about a dozen ugly chunks and my leaf blower on it but it's still above ground level. I'll be lighting it up again this weekend.
I’ve had several soft wood stumps burn out below the ground with one try, but they were always dry/dead. I sawed some draft ports in the bottom of this one, seemed to draft well. A piece of sheet iron/tin on the top would probably help too.