Everything is written here, although in English.
Here's the gist of it:
All creatures and destruction spells are linked to one of the 4 elements of the world: Air, Earth, Fire, Water. And Heroes of the Dungeon can deal additional damage by sensing these elements. This is their special ability called Elemental Chains.
What is needed to activate Elemental Chains:
1. The Elemental Vision ability.
This allows the hero to see which elements the enemy creatures are linked to. This ability allows you to deal additional damage ONLY with spells.
2. The Elemental Altar building. Building it allows you to see which element your own creatures are linked to. Now, your units can also deal additional "elemental damage," not just spells.
It is important to know that without the Elemental Vision ability, building the Elemental Altar will have no effect.
In order to deal "elemental damage," the attacked creature must have the opposite element to the attacking creature, or to the attacking spell.
Elemental opposites:
EARTH --- AIR
FIRE --- WATER
After dealing "elemental damage," both creatures involved in the battle will randomly change the elements they are linked to.
The additional damage is calculated as a certain percentage of the standard damage!
The Elemental Vision hero ability gives 5% "elemental damage."
Hero skill:
Fundamentals of Irresistible Magic gives +5%
Advanced Irresistible Magic +10%
Expert Irresistible Magic +15%
Master Irresistible Magic +20%
Upgrading the Elemental Altar to the Primal Altar gives +10%.
The ultimate Elemental Fury ability doubles the "elemental damage."
The elements of creatures are displayed in battle on their icons.
Here are the elements of spells:
Magic Arrow -- Fire
Stone Spikes -- Earth
Ice Arrow -- Water
Lightning -- Air
Fireball -- Fire
Ice Ring -- Water
Chain Lightning -- Air
Meteor Shower -- Earth
Armageddon -- Fire
Explosion -- Earth
Enemy creatures do not deal "elemental damage," regardless of the elemental opposition, unless your enemy is another hero-warlock.
Luck also increases "elemental damage."
If the fighting creatures are not of opposite elements, then neither "elemental damage" nor the subsequent change of elements will occur.