Calamity is the third and final volume of the Reckoners trilogy. My general opinion of it can be summarized as "I really regret this series isn't continuing because I liked it enough I wanted to read more about it." The Reckoners shows just how good a really good superhero novel series can be and ranks up there with Soon I Will Be Invincible for works I really enjoyed. It's not my favorite individually but works well as a collection.
The premise is the world has been covered in superhumans (called "Epics") by a mysterious event called the Calamity, which turns out to be a being from another dimension. Every Epic was corrupted by their powers, twisted to becoming a selfish sociopath for reasons unknown but tied to their worst fears. In the previous volume, Firefight, the anti-human resistance's leader has been corrupted by his new superpowers.
Surviving Reckoner, David Charleston, has joined with his girlfriend Megan to fight against the Professor. More than defeating their old friend without killing him, they intend to take the fight against Calamity itself. If they can defeat the source of all Epics, they believe they can return the world to the way it was before the superhuman apocalypse.
Calamity has a lot of really good gut-wrenching moments which come from the fact the Professor's transformation to Phaedrus means they have an enemy who knows all their weaknesses. Brandon Sanderson doesn't hold back in killing beloved characters and the stakes raise continuously throughout the book.
Much of what I disliked about Firefight is absent from this volume with the Megan and David relationship feeling less forced. While I can't say I really ship them, they didn't annoy me nearly the same way they did before. They also work as an interesting deconstruction of the central theme of how Epics are driven by fear while selflessness is driven by love. Yeah, it's "the Power of Love fixes everything" but maybe I'm okay with that message.
I really liked the new character of Larcener and the encounter with Calamity in order to find out the origins of Epics. We also get a follow-up to David's origins in losing his father at the bank massacre by Steelheart. That singular event shaped David but could have gone very differently depending on his father's actions. By discovering what would have happened but for want of a nail, the history of the setting is expanded.
The Professor makes a truly impressive villain and he is even more capable than the monstrous Stealheart in harrying our heroes. Unfortunately, due to the nature of his corruption, it means that his personality reverts to nothing more than "evil." My biggest complaint with the setting is that the nature of Epic power corruption means that they're all one-dimensional. I would have been more interested in a Professor who had decided, of his own free will, to become a bad guy but that's not really something Brandon Sanderson was interested in exploring.
In fact, I was far more intrigued by the characters of Obliteration and Calamity as villains because it was their own personal flaws which made them evil. They were a religious fanatic and misanthropist supreme, respectively, who had reasons for their actions. I wanted to know more about how they had come to be as they were as well as see them play off the others in the setting. Still, I have this very high bit of praise for Calamity: if Mass Effect 3 had ended with Calamity instead of the Star Child then it would have probably been accepted as a decent ending.
There's some really good emotional moments spread through this novel and I have to give credit to Brandon Sanderson. We get to see David and Megan pushed to the limit as they watch their allies taken down by someone they deeply care about. We also get to see both of them confront their deepest fears, in fitting with the theme of true courage coming from overcoming one's weaknesses than fearlessness in general.
The ending for the novel also nicely wraps up most of the major story arcs for the world but not so much that Brandon Sanderson couldn't pick up the series again if he wanted to. That's the best kind of ending in my view. There's a lot of good in this book and it really builds on the previous volumes.