Souls of Dragontale AU (My friend's commission)

So it's been a while from not using my Wattpad, 'cause I'm busy playing my xbox...still, my friend chatted me about her ideas from Dragontale AU; she told me about a souls of humans which is reference to Undertale, they are the most powerful humans souls in the world to stop evil, chaos, and other apocalypse.
Now, I have a task to create them using my crossover characters in my AU. So the readers would think that these characters were a Legendary AUs much like a codex for Frisk. This should be a while to progress the story.