@gagegageha
Bad guy wants to unseal evil dragon for the sake of chaos, but he's not strong enough to defeat the seal (the angel).
So, he used MC and his friends to do it for him.
MC can easily stop him, but he wants info first. So, he goads evil guy into monologuing.
Originally, the Elves had to sacrifice 12 High Elves to seal the dragon. There currently aren't enough High Elves alive to reseal the dragon now.
The evil dragon was split into 12 pieces and each sealed away. Evil guy and his colleagues are all targeting one each.
Dragon is technically an illusion (evil guy said it himself), so it can be destroyed in the same way as the angel: taking enough damage.
Evil dragon has ability to suppress people with its vision, but MC too stronk.
MC is obviously strong enough to one-shot it, so he did.
Evil guy was using remote transmission to avoid retaliation, but MC can apparently cut through f*cking space and still kill him because too stronk.
Understand now?