According to simulations run on different futures of Ignis and humanity, Revolver says that Lightning's is the only one that leads to mutual destruction.
The Light Ignis thought 
the Ignis were imperfect.
Warum betrachtete das Licht-Ignis
euch Ignis als unvollkommen
Sé por qué el Ignis de Luz
pensó que eran imperfectos
O Ignis da Luz achou que
os Ignis eram imperfeitos.