The game's first chapter is about cleaning and healing the nature. The lands have been corrupted by dark-ooze and the only way to stop it from spreading all over the environment is by cleaning it. The corruption may spawn vile creatures, who might attack and you might need to be prepared for defense. Use your cleangun to shoot foam that corrodes the vile spread.
Unfortunately the corruption has drained nature's nutrients and energy. After abolishing the spreading corruption, the lands are dry and lifeless. Use your hydration crystal to cast a spell, which hydrates and nourishes the soil. Plants which died due to the vile invasion will regrow once the environment is suitable and nourished.