""In the Step System, players wanting to perform an action determines their level or "step" for the skill, talent, or ability to be used. This step can then be looked up in a list of dice to be thrown.
Examples of steps Step Dice to be thrown
9 1D8 + 1D6
14 1D20+1D4 or 2D12 (Earthdawn Classic option)
The result of each die is added (dice which reach their maximum value are thrown again, adding each maximum to the tally, along with the final result below maximum) and compared to a value decided by the game master/storyteller according to the difficulty of the task. This approach allows for impressively high scores with high level characters, yet leaves room for possible failure. This will sometimes make combat last longer than in other games."
Source: Wikipedia, "Earthdawn", available under the CC-BY-SA License.