Avatar Book 2 Earth Episode 13 - The Drill Episode Title:The Drill.Episode Description:Having successfully crossed the Serpent's Pass, Aang is determined to go to Ba Sing Se where he hopes to find his lost sky bison, Appa. However, he discovers a Fire Nation drill commanded by Azula heading straight for Ba Sing Se, intent on penetrating the wall. Battling against Azula, Mai, Ty Lee, and contingent of firebending soldiers, Aang and the group succeed in stopping and destroying the drill from the inside. Meanwhile, Jet wishes to recruit Zuko for his Freedom Fighters, but then learns that Zuko and Iroh are firebenders after deducing that Iroh used firebending to warm up a lukewarm cup of tea.