The metabolism of Orcs and Goblins is completely unlike that of Humans, Elves, Dwarfs and most other races. This has profound effects on the way Orcs and Goblins react with the world of magic. Other creatures draw upon the raw power of the winds of magic, but Orcs and Goblins generate their own.

Every greenskin unconsciously generates a weak magical field, perhaps as a reaction to the surrounding magical field of the Warhammer World. During the intense excitement of battle this field becomes stronger and merges with the magical fields of all the other Orcs and Goblins around him. This gives the greenskins a feeling of communal elation and invulnerability known as the Waaagh! When the Orc Boyz march into battle they feel strong and unbeatable as the mounting power of the Waaagh overtakes them.

As the Orcs become more excited the energy of the Waaagh grows stronger and stronger until it reaches a critical point when the pressure is so intense that it has to discharge itself or burst. The Waaagh always discharges through the most receptive mind, that of an Orc or Goblin Shaman. As the Waaagh intensifies a Shaman feels the pressure building up in his brain, driving him wild with excitement and pain.

Fortunately Shamans learn at an early age that the only way to avoid extreme pain (and worse) is to allow their minds to release the mounting energy in the form of a spell. In immature Orcs this takes the form of random explosions and unconsciously generated poltergeist activity in which objects mysteriously fly about the room and smash against the walls. A mature Shaman learns how to control these powers and turn them to his advantage in the form of powerful energy blasts and radiant spells of destruction.