Professor Jonathan Phaedrus has become the most dangerous enemy of the Reckoners -- the tyrannical Epic Limelight. 
 And unfortunately that is only the BEGINNING of the problems in "Calamity," the climactic finale of Brandon Sanderson's superpowers-with-a-catch Reckoners trilogy. The book starts off rather slowly compared to the previous two books, but it revs back up when the heroes make their way to Ildithia -- a grim, action-packed tale that breathlessly moves toward the ultimate clash between Reckoners and Epics. 
 Only a small number of Reckoners remain after the disaster in Babilar, including David, Mizzy and a newly-rejoined Megan. After a brief trip to Knighthawk, the inventor of the motivators, they set out for the latest place that Phaedrus (aka Limelight) has gone -- Ildithia (formerly Atlanta), a moving city constructed of crystalline salt. He's in the process of completely taking over the place, seeking out the power-stealing Larcener... but David is convinced that Jonathan Phaedrus is somewhere inside Limelight, and that they can redeem him. 
 Their only ally is Larcener himself, a bratty Epic who doesn't want to actually fight, and their only weapon is Megan's mysterious reality-warping power. But their attempts to stop Limelight lead to a vicious battle, and the discovery of a devastating plan that could give him the ultimate Epic power. The only chance for the human race is if the Reckoners somehow neutralize Limelight -- and even if that happens, what about Calamity? 
 In an odd way, "Calamity" is written more like a middle volume than a grand epic (joke!) finale, with most of the focus on defeating Limelight/Phaedrus rather than on the sinister force of Calamity itself. It also begins in a rather slow fashion for a climactic story, with a long stay at Knighthawk's castle -- it feels more like a novella than a part of the overall book, even if it is quite essential to the story, and left me itching for the main adventure to start. 
 However, things pick up when the Reckoners make it to Ildithia -- Sanderson weaves together a trio of dense subplots into the main plot about battling Limelight and Calamity, and packs the entire story with plenty of explosive, flaming, light-spear-flinging fights. It hurtles towards its climax with almost breathless speed, occasionally darting into the parallel universes that Megan is able to access, only to twist back into the conflict with Limelight. And after that story, Sanderson shoots us right into the grand finale, a cosmic twist that will blow your mind. 
 It's also a much grimmer story than the ones that came before it, just because of the awareness that this is the last stand against the Epic domination. Thankfully David's eccentric ways keep a little quirky humour in Sanderson's robust writing ("We were specks of mud on the window; he was a giant, vengeful bottle of spray cleaner"), and his earnest belief that he can redeem the Epics he's known is somehow uplifting in the midst of all the bleakness. 
 In fact, David remains the bright spot of the series -- earnest, optimistic and determined to never give up in his quest to stop the darkness that consumes the Epics. Sanderson delivers some emotional gut-punches through his hero, particularly when David discovers the emotions that ultimately fuel the Professor. And his purity of spirit is something that seems to radiate to all those around him, forcing everyone -- even those who see only corruption and darkness -- to see the world the way he sees it. 
 While the pacing is uneven and the ending a bit abrupt, "Calamity" is so powerfully-written that it makes you wonder if Sanderson has the Epic power of writing. A solid finale to this outstanding trilogy.