Once more, with feeling!

2x01 - The Avatar State
2x02 - The Cave of Two Lovers
2x03 - Return to Omashu
2x04 - The Swamp
2x05 - Avatar Day
2x06 - The Blind Bandit
2x07 - Zuko Alone
2x08 - The Chase
2x09 - Bitter Work
2x10 - The Library
2x11 - The Desert
2x12-13 - "Secret of the Fire Nation" (The Serpent's Pass & The Drill)
2x14 - City of Walls and Secrets
2x15 - Tales of Ba Sing Se
2x16 - Appa's Lost Days
2x17 - Lake Laogai
2x18 - The Earth King
2x19 - The Guru
2x20 - The Crossroads of Destiny

Fake OP 2