The Harbinger is a Pact Magic using Spellcaster akin to the Warlock, but rather than having a Patron to contend with, the Harbinger faces a Dark Fate. In truth, condemning your foes to terrible fates is fun and effective, though you may spend some of your time warning your allies that the sky is falling (don't worry, no Chicken Little'ing here, the sky will eventually fall if you say it will).
Early in your career you'll intone dire curses on your foes to better help them meet their end. You can gradually weaken this Doom Curse to further diminish your target's abilities at critical moments. Almost like the opposite of a Bard's Inspiration feature.
Your most dramatic power is the declaration of Impending Disaster. A target of your Doom Curse or a nearby location might be struck with a terrible disaster ranging from Magic Missles for all to a Meteor Swarm. You can try to invoke the disaster sooner though doing so lessens its power.
- from the publisher's blurb