The treant flails as it suddenly finds itself carrying an unexpected passanger, snatching at Spreagadh with it's smaller branches, but being not the most spritely of creatures it's far, far too slow to actually catch the elusive fey. Flame explodes around it's crown of branches and soon has nearly all of the tree ablaze, but the spell of stoneskin carved to the treant's bark protects it. The treant's innards are all too vulnerable to flame, but stone is far less flammable.
With a roar it starts forward, pointing one of it's 'arms' at Spreagadh's new hiding place. From it's closest analogue to a finger lances out a spear-shaped gust of razor sharp wind, capable of cutting as well as any knife or dagger.