One issue I had when filling out the 150+ Illborn was the distinct lack of enemy variety in TWoOtA itself. For example, the known enemies of DL2 are Wisp, Big Wisp, Scanbot, Searchbot, and Cleaner. In the forum game, this is largely a sanity saving measure as players can blow through enemies and floors fairly quickly when it's updating, but in the video game, each floor has enough content to fill an entire "episode" (game update).
There was one other Pokemon-based series that had this problem: Touhoumon. Even Touhou's gargantuan cast wasn't enough to fill all the Pokedex slots. Their solution was the addition of two to six "forms" for each character, starting from Chibi and branching off into Evolved, Attack, Defense, Speed, Technical, and Advent. Nearly every puppet had a Chibi and Evolved form accessible through the normal methods, but you could find evolution stones (or Touhou's equivalent) to branch off your Chibi puppet to its other forms.
TWoOtA will be stealing this neat mechanic. In the Dark Cathedral, you can sacrifice your beloved evolved Illborn to create Attack, Guard, Technical, or Special essences. These Essences can be used to evolve Illborn that have not yet reached their normal Evolved form. Most alternate evolutions have not been seen in TWoOtA, but the Special Essence cameos may look familiar.
Example...
Wisp evolved at level 18 and becomes
Big Wisp, but with a Technical Essence, it becomes
Will-of-Wisp, a useful Electric/Fire variant without the signature Shocking Spheres move.
I look forward to seeing the interesting team combinations this feature results in. The main boss battle of Episode 1 was finished today, and it contains some of the variants that will become available in Dungeon Level 3.
We're in the final stretch now!