Found on p. 42 of the Warhammer: Skirmish rulebook Slayer! pits six intrepid Troll Slayers against one mighty Giant. Should the Slayers prevail, 100 points of Slayers would be added to the Slayer Army of Karak Kadrin in the big game, reinforcing its bid to seal off the tunnels to the surface. If the Giant wins, the Orcs & Goblins on the surface would be able to purchase a Giant for that battle at half price.
Read more about this scenario over at the Wayback Machine here, here, and here!