With a rasping, whispering sound like the breeze rustling branches on a dry October morning, a sound that might be it's version of a laugh, the treant plunges it's lower right hand into the dirt. The forest around them begins to wither visibly as it reaches out and draws power from the trees, the undergrowth, the lowly things that crawl beneath the loam, focusing all these stolen energies into a single patch of earth, dead in the wave's path.
As Spreagadh's spell crosses this focal point, the trap is sprung. The ground beneath the wave explodes upwards, with enough force that it is all but certain to stop or at least slow the attack's progress. This tricky little number does not leave enough time for the treant to counter-attack, not immediately, but it's working on something nasty.