User blog comment:Kogath/Monster Hunter 4 Ultimate for the Nintendo 3DS/@comment-28303251-20151014210824/@comment-5043481-20151017164647

Assuming you already have some, here is how to use it. First, get the cannon to the demolisher. The barrel will swing down and lock with a pipe on the wall. Next you have to stand next to the cannon button and use the dense marcoal with Y like you would drink a potion. It won't do a thingy like ballistas where you can just press a to use it.

It lands on the big brown burnt spot near the dragonator.