Considering the Marvel film Deadpool II we open up with Deadpool detonating himself on a warehouse full of explosives, and then he tells the story on how we got there. That was one "book," however, and we know that works well.
Now my series ends with somewhat of a clash of the titans action scene, and I though of putting these biggies at the climax as an opener. The problem is, no one knows they are "biggies" until you read the first two books. The action is amazing and all, but you did nothing yet to develop them. It's just an epic conflict and in a quick dialogue, you feel equally pulled toward wanting each to win. Now, the first book develops one character almost exclusively. The second book develops the second character. The third puts their mores and needs in direct conflict, and brings the series to a close.
I am concerned about leaving at least the first book with a dry ending. It has a good conflict and resolution by its own right, but it only brings hints of the bigger story along, leaving the finale dangling.
One really bad execution of this makes me concerned. A TV series called Manifest opened with a passenger plane vanishing for 5 years, only to land in New York with no one aged at all, or having any idea that they were gone. They dragged this series on for three years and it got canceled. Not only did they not revel where the plane went, they simply piled on more plot devices in every possible direction. So, Manifest has many problems besides the interminable mystery, but for my question here; is it a mistake to tease your series finale in book 1 of 3?
As it stands I have a couple versions of the open lined up, but the finale is amazing in my opinion. I plan on leaving them on a cliff already, is that cliff too high?