How to Unlock Thunderstorm Spell
Emerald Tablet – Volume VII is found with an Orb in an Orb Room. To find it, you must pass by a lava lake (using a water based spell or pouring potions on it), jump into a pit right next to it and climb a wall made of Extremely Dense Stone. The pit can also be used to skip levels. Picking up the Orb unlocks a Thunderstorm spell!