I saw someone point out something on reddit so I went back to check (MAJOR Spoiler below!)
In Rel's Speech she mentions 9 (Nine!) people
4 destruction
2 Creation
2 Conduits
1 intergrated entity
But if you count the number of people who came with us to Estalucia it only adds up to 7!
This image below is my best guess onto who is what role?
As teased by the final Chapter Ferry also managed to hitch a ride to estalucia
However, this is where to mystery of the integrated entity comes in
Because we have three possibilities
Gran - Part Primal and Skydweller
Gallanth - He's been in Estalucia for couple of years could be considered integrated
Ferry - She's dead and technically a lost soul so it would make sense that she got ported to Estalucia so she could an integrated entity
However no matter which way you slice it we are still missing one being of destruction
As for my guess, I'm betting on Proto Bahamut and yes I know I'm bias for the dragon, but I have an argument for this
It can't be Rein or God Bahamut because Rel was surprised that God even showed up in the first place so it rules those two out
Secondly, Proto bahamut is the unofficial 4th member to the iconic trio so as a result it wouldn't be a surprise to Rel that Bahamut did also tag along.
