How will Relic factor into future events? Will he relate to the Trinity War somehow? Why and how does he attempt to destroy the corps? Why does he appear to have cybernetic enhancements? I know all we can do is speculate at this point, but I'm interested in hearing theories.

I know that he is going to be a big threat in the future and he may be the one that turns off the green lantern central battery. He wont have any part in trinity war since it seems he is gonna be just a gl villain. Im not sure why he wants to destroy the corps. As for the tech on his back it kind of looks like one function of it could be distributing a yellow venom like substance(similar to what Bane uses). An idea that I had was that he could try to capture the life entity or something similar since the entity is on the teaser page. we will be getting an issue dedicated towards him in September for villains month, so hopefully we will get a lot more of his backstory.

Most likely.

Hopefully he will make a little (or a lot) more sense than the First Lantern and Third Army did.

Was he a pre-existing villain before this story.

Nope