In regards to the "Warrior of Darkness"; how far is too far?

[Nestama]

I don't think we'll be doing anything the First's Warriors of Darkness did. They were from a Shard that was going to be returned to the Void (Flood of Light) and Elidibus told them they had to cause a Calamity on the Source to save it. What Elidibus probably "failed" to mention is what may happen to a world that goes through the 'Rejoining' process. While the threat of the Flood is gone, what happens to everyone/thing that lives on that Shard (based on what was said in 4.5, it's implied they cease to exist)? If it wasn't for Urianger, Zodiark would probably be revived and the First, Warriors of Light and Scions present during the fight would have likely perished.

For our characters, it's probably just gonna be fighting/killing as many light-based things as possible so there can be balance. Watch Minfillia end up being the final boss lol