If you enter a room, get a flame next to the hexagons neighboring another entrance, if before leaving you get a Firebug to go to that other entrance, when re-entering sneakily by that other entrance, the Firebug will be moved without triggering it's "explode-near-fire" ability (and be attackable.

Steps : 

1- Enter a room with a Firebug
2- Get a flame 2 hexa from another entrance (0 hexa being right where you can use a door) WHILE getting the Firebug at that other entrance.
3- Exit room and enter via that other entrance
4- Realize the Firebug is near a flame and hasn't exploded in flames