The DC Universe has had many cataclysmic events play out, such as Crisis on Infinite Earths and Blackest Night. Now, Knight Terrors is unfolding, breaking into the minds of many heroes and villains. It's all due to the demonic Insomnia probing to find the location to the Nightmare Stone -- something that'll give him unlimited power.
Source：https://www.cbr.com/knight-terrors-joker-batman-kill-policy/
