You said the druid is APPARENTLY human, which means he might be something else that can shapeshift into human form.
This opens things up to a variety of lycanthropes, ogre magi, rakshashas, certain dragons (with Druid levels!), and dopplegangers, among other creatures. Just food for thought.
Druids have the spell Quench, which puts out fires AND temporarily shuts of fire-based magic items.
Wildshaping into innocuous forms and using Natural Spell to wreak havoc could be fun... by alternating forms and lairs, the PCs may never get enough info for a successful Scry-Teleport assault.
FFG has Wildscapes, which in turn outlines rules mechanics for operating in various terrain, to include forests.