Diablo 3. For those who have forgotten -- it's been a while since BlizzCon 2008, after all -- Diablo 3 players can modify every class skill with a runestone. In the early version of the system, runestones came in fairly self-explanatory flavors. A multistrike rune, for instance, would add extra hits to a given skill.
Now, Blizzard has revealed the latest version of the rune system, which has undergone a few changes. There is a set number of rune types -- five, to be exact -- though each type won't behave the same way for every skill. For example, an indigo rune will add fire damage to the Monk's Sweeping Wind skill. The same rune completely changes the Wizard's Ray of Frost, turning it from a piercing ice beam into a swirling blizzard that surrounds the player.
Head over to the Diablo 3 website to learn more about runestones and check out videos of their effects in action.