Make a Spellcast Roll (16). Once per rest on a success, all targets within Very Far range who aren't flying must make a Reaction Roll (18). Targets who fail take 3d10+8 physical damage and are temporarily Vulnerable. Targets who succeed take half damage.
Additionally, when you succeed on the Spellcast Roll, all terrain within Very Far range becomes dicult to move through and structures within this range might sustain damage or crumble.