Immobulus is a very handy spell, and has certainly done the trick in getting the Whomping Willow to stop thrashing, but unfortunately its effects don’t last forever. Soon enough the tree started to move slightly; the first traces of it waking up.

Within a few minutes, it is back to THWACKING all over the place. The use of fire has agitated it further. It’s a good thing that you attached the cauldron to the workstation because there is a good chance that a branch might hit it.