MASSIVE Plot Failure
Well, it's a good thing for the Humans the demons are STUPID (or at least highly unmotivated). (Or perhaps just interested in HAVING FUN!)
Why waste so much time worrying about Denzel if you want to cause the Apocalypse?
With all that demon power, it would have been SO EASY to start murdering people by the dozens. Cops kill you? Move on to the next body, no problem. Kill a bunch more that day. That Azalea (hee hee) could have taken out hundreds of people every single day.
The poor ending to the film only proves my point. "20 more murders on your scorecard"(or whatever J. Goodman says there at the end.) Only 20? Why? Why not kill a couple hundred? And then do it again? And Again?
"Dude, it's Lord Goblin King, not Lord Go Blinking!"