Runes in Diablo 3
Initially, a small excursion into history. Runes appear in Diablo 2 LoD – they were items that can be inserted in the socket armor and weapons. Beside the properties that give the runes can be collected some runewords, and receive a special set of properties.
In Diablo 3 on such a concept rejected (though can still beat a hundred times). Now, runes are not things improve, but … Skills (Skills)!
With the change to skills is not easy – a little harder to beat, or more range, but mostly skill varies dramatically. Examples of changes in skills a little further, but for now consider the types of runes, there are 5 types: Crimson, Indigo, Obsidian, Golden, Alabaster.

The same runes are divided into grades, with 7 levels of “coolness” of runes, the first 3 levels will meet the players on the complexity of Hormal, 4,5 levels of the runes will meet on a Nightmare and the last, 6 and 7 levels of complexity in Hell.

In the demo version of the game presented at BlizzCon 2009 runes looked like this:

Now, about the change of skills (skills) with runes. At this point, the assurances of the developers of this game still in raw form, for example, for the class hunter of demons and still not invented by the properties of the runes. What is known:
Changing the skill is only improves the side.
In a change of skill will be a random factor.
Improving the runes can be removed, stored there with Fleece – remains a question.
Change of habit change and its visual part. The developers say that the runic system takes them a huge amount of time. All in the game about 150 skills and add to it 150h5 = 750 modified skills. In sum, they have to “draw” 900 types of skills.
Each type of rune gives a unique skill change, and the developers are trying to make each type of change, playable, thus creating an infinite number of ways, “pumping”, but generally include the following changes:
Alabaster – major changes (Wild card functions).
Crimson – adds fire damage.
Golden – reduces the requirements (mostly MP) skill.
Indigo – multiplies the skill (for example, instead of one faerbolta flies a few).
Obsidian – major changes (Wild card functions).
Only for some runes can be assumed to change, for others the changes can be found only practical way.
Consider the properties of the runes on the example of the ability of toads Plague (Plague of Toads)
In the original form of skill creates frogs that attack enemies (translation skills are not quite sure who knows best – write.) With improvement:
Alabaster – Toad extra dazzle enemies.
Crimson – Fire Toad inflict additional damage.
Golden – reduces the mana cost.
Indigo – creates a “rain” of frogs that attack at the point indicated.
Obsidian – creates one permanent huge frog, which eats the monster entirely. Maybe eating some of the leaders (possibly at high levels runes), but not the bosses and big enemies.

Consider the properties of the runes on the example of the ability to Hydra (Hydra)
In the original form of skill completely moved out of Diablo 2 – Sorceress creates in the location of fire hydra that spits fireballs at nearby enemies.
Alabaster – creates purple hydra, which attacks the “secret” injuries (apparently changing element attack).
Crimson – creates the blue hydra, which attacks the pieces of ice.
Golden – creates a giant hydra, an attack which causes damage to the area.
Indigo – blue creates a hydra, which attacks the lightning that never miss.
Obsidian – is the green hydra, attacks which are poisonous in nature.

Kravt and better runes.
The developers have confirmed that Mystery (one of kravterov in the game) will be able to create and improve the runes, although there is no specificity in this process.