Zig Zagged: Fire, Ice and Lightning are only the first abilities the characters learn. Later, they also learn a bunch of other abilities. However, they still continue to use the three first most often and most effectively.
There's no system of Fire, Ice, and Lightning in Heroes Of Troperia.
Fire, Ice, and Lightning are just three of several elements in the game, which also include Water, Shadow, Earth, Wind, Light, Metal, Sound, and more.
Enforced: They make the flashiest special effects.
Invoked: An ancient sage sets up a magic system using the 3 elements for future mages to use.
Exploited: The Big Bad built his armor to withstand all 3 elements.
Defied: An ancient sage reminds his students that the magic system does not have to be limited to the 3 elements. He also encouraged them to go ahead and explore all other possible elements and create spells based on them.