Awesome / Better Living Through Science and Ponies

• Everything Princess Celestia does in the extra chapter, especially the Olympic-level trolling.
• GLaDOS throughout the story is at her most sinister and badass. She gets some great moments as she psychologically tortures the ponies, but what really took the cake was turning herself into a giant robot pony and beating Chell senseless.
  So, Chell.... Think you can kill me now that I can actually fight back?
• Chell taking full advantage of having four portal guns by setting up a four-way laser to slice through GLaDOS' control center.