I'm not going to link them all that take too much space but I'll tell you the name of the cards part of my evidence and explain my theory. First the cards then my theory

Ethereal Healer
Stalker of Marabas
Firegut Zombie
Contract Killing
Elusive Specter
Wailing Wraith
Charred Zombie
Purging Flames
Sealed Tomb
Decaying Giant

These reward cards have a distinct 'horror' theme to them and in fact Firegut Zombie alludes to the rumors of corpses imbued with Ruby gems on them from the lore pages. Also note there are three cards with a tomb on them Purging Flames Sealed Tomb and Wailing Banshee. This tells me that Purge and Seal cards are in fact part of same graveyard. Sealed hints at a ancient tomb sealed off and the art has it opened which is bad enough. Later we see Purging as if they had to engulf the crypt in flames to make sure the corpses stay dead. Also note that in Cory's PCgamer stream he had a quest of Finding source of zombies. This tells me due to wording it's a everyone involved(all eight races) quest it seemed too big to be just a quest. Also on the map before we see Cave-In there were some nodes with a green one possibly dungeons(?) and the one closest to Cave-In looked like a haunted house.

So my idea is that many dungeons explore clues as to what the Hex is going on (Scooby Doo reference anyone?) and gives rewards based off the overall plot. I was at first annoyed at the lack of flavor text but now that I'm frantic on this theorycraft of mine I think the artwork has lots of lore to it. I can't wait to read the lore in Chronicles.