There are 4 types of elements in Shaiya. Water, Fire, Wind and Earth. Mobs can be off any of those elements. Which element works best against what enemy is something a good mage must know.
WATER spells deals 50% more damage to FIRE creatures
FIRE spells deals 50% more damage to WIND creatures
WIND spells deals 50% more damage to EARTH creatures
EARTH spells deals 50% more damage to WATER creatures
So this means that - Water > Fire > Wind > Earth > Water. Using wrong element will result in 50% less damage.
But some enemies and spells are non-elementary. All element spells deals 25% more damage to non-elementary enemies. And non-elementary attack deals 25% more damage to all elementary creatures.
So next time you use your wind storm on fire mobs, think again what you are doing. ^^