Urcian Elemental Magic

The Great Kingdom of Urcia was a high-magic realm powered by arcane interactions with the elements. During the Final War, during which the Enemy Gods sent the gargantua to destroy Urcia, the Great Kingdom's mages cast numerous defensive spells to protect themselves against the great monsters from outside. In the last thousand years, these ancient spells have become warped, cracked, and faded. Nonetheless, with the return of the gargantua, the spells have reactivated. Now these broken spells attempt to serve their old purpose, defending Midavel against the gargantua, but they take effect essentially at random and rarely have their original intended effect.
Many of these spells are precursors of the magic ultimately used to create the genasi, the defenders of the Interment Gates. Thus they are transformative in nature. Others take the form of abjurations around a particular place or item.

The Classical Elements

Earth, air, fire and water were celebrated and widely employed by the mages of Urcia, who bent these classical elements to their will in the war against the Enemy Gods. Many great weapons ran on classical elemental power, and the four genasi subraces were created along these lines just before the destruction of magic.

The Abstract Elements

The Urcians also knew of numerous elements said to represent abstract concepts. These included time, riddles, music, beauty, community, history, sleep, and empiricism.

Clues

Revealed

• Earth magic transformed the living island "back" into stone, but caught its denizens as well
• Water magic transformed Marva into a sea hag

Unrevealed

• Some sort of fire or air defense against Silence, the gith, in 3.2
• A riddle elemental that attacks via Int save vs. psychic damage, unless you can answer a riddle (like the player has to actually solve it during the fight)