What if, the Letters in the Title Screen for various episodes of the original Avatar TLA were made out of what the episodes were focusing on or featured.
There can be overlap but these are the episodes with dedicated elements.
The Boy in the Iceberg: Water
The King of Omashu: Earth
The Crossroads of Destiny: Green Crystal from the Ba Sing Se Catacombs or Lighting.
The Puppet Master and The Southern Raiders: Blood (The two episodes where Bloodbending is used)
The Guru: Metal (Toph Develops Metalbending)
The Winter Solstice: Lava (Roku, via Aang, destroys his temple with Lava)
Imprisoned: Hot Coals
The Warriors of Kyoshi: Paint from the Kyoshi Warriors' Faces (Meet the Kyoshi Warriors)
The Southern, Northern and Western Air Temple: Air
The Firebending Masters: Iridescent (Rainbow) Dragon Fire
The Swamp: Vines (First Plantbender)
The Desert: Sand (In the Si Wong Desert)
The Storm: Thunder Clouds (Iroh Redirects Lighting)
The Day of Black Sun: Shadow (Solar Eclipse)
Sozin's Comet: Energy from Energybending
The Beach: The Sun but also Combustionbending
The Chase: Azula's Blue Fire
The Avatar State: Lightning (First Appearance of Lighting Generation)
The Waterbending Master: Ice
The Siege of the North: Spirit Water
The Blind Bandit: Seismic Sense