User blog comment:Wolf night10/The Final Getsuga Tenshou/@comment-3557163-20110418210829

The Getsugatensho (translated as heaven piercing lunar fang) is just an attack where Ichigo compresses his spiritual pressure into one blast of energy. It's name implies that it is a fang of the moon that has the potential to pierce heaven, and if you've seen the Final Getsugatensho, you'd say this is true. Just as the getsugatensho to compress his spirit energy and fire it through his sword, the Final GT is similar, only it takes ALL of Ichigo's spiritual energy into one final attack that would finish off almost any powerful enemy. However, this attack completely diminishes the user's pool of spirit energy, thus leaving them powerless.