Some thoughts:
1) what do you mean "he knows the incantation"? I don't remember him using "Loki" before, the only other verbal transformation spells he had said before were "cherusil" and "quartz quartz".
Though it does bring back to mind how the spells in this series build on each other as a foundation for more powerful spells, like how "cherusil" (transformation) and "quan quan" (reflects the user's personality) serve as a foundation for "quartz quartz"
(Reading this out loud sounds like I'm being censored)
2) Ali became Delkira! This... isn't as surprising as finding out how many folks here still on the fence about that, I had thought that big question here was "Does Ali know/remember he is Delkira" and maybe this chapter is hinting that he's starting to (maybe?)
3) Iruma becoming more of a demon. We've seen this a lot now, but what's really fun are the feathers. Iruma is really tied to dark feathers since his 'evil cycle" manifested, which is interesting because the trasformation magic Iruma's learned and the power of the magic is very tied to him (desire and personality) rather than the power he gets from Sullivan.
So it's possible that the demon form he takes here isn't what he imagines himself to be, it's the form that reflects Iruma the most (which lends more to his connection to Delkira cause the shape of their horns are similar).
Do I think it's permanent? No, not really, the spell is called "Loki". The names and characters from this series have referenced traits from their namesake/source, so It could just be a more tangible transformation (whatever that could mean) that's temporary.
But I could be absolutely wrong (not the first time) and there might be permanent changes in the next chapter! Either way, the implcations are:
-Delkira transformed into a human and became iruma's parent.
-The mind and power of Delkira are in the ring, and iruma is his body transformed into a baby and grew up in the human world.