Waves Of Madness

In Swamp Thing, Volume 2, Love And Death (New York, 1990) by Alan Moore, the Swamp Thing's former adversary, Anton Arcane, escapes from Hell:

"The returned man chuckles...
"...and a shockwave of nightmare ripples out across the sleeping continent...
"..and in Lafayette, Jody Herbert comes across the wino passed out in an alleyway and Jody has a box of matches in his pocket and there's nobody else around...
"...and in Alexandria, Tina-Louise Pierce says 'The hell with it' and lifts the ancient iron frying pan that her husband is too cheap to replace..." (p. 57)

In The Sandman, Volume 1, Preludes & Nocturnes (New York, 1995) by Neil Gaiman, the Justice League of America's former adversary, Doctor Destiny, escapes from Arkham Asylum for the Criminally Insane:

"News at Six. Is everybody going crazy? Reports are coming in from across the state about a wave of madness, suicide and bad dreams..." (p. 169)

"Listen: you can hear the screaming.
"Three children are trapped in an elevator with Bobby-Joe McCann.
"Harold Smith prowls the dog's home, a tire iron clutched in his bloodied fist.
"Maude Carillon screams with laughter as the flame devours the geriatric ward.
"Listen." (p. 185)

In both cases:

a villain returns;
there is "...a shockwave of nightmare..." or "...a wave of...bad dreams...";

named individuals, not continuing characters but created for this single incident, commit acts of horrific violence.

Reading The Sandman reminded me of Swamp Thing so I checked back and made the comparison. Arcane brings supernatural power from Hell whereas Doctor Destiny wields a stolen dream-stone.

In Swamp Thing, in Arkham, Woodrue bangs his head on the door and Two Face has to be sedated but the scariest thing is when the Joker stops laughing (p. 68). In The Sandman, the Scarecrow asks the escaping Doctor Destiny to tell the Joker to hurry back because "It isn't April Fool's day without his little jokes..." (p. 135) and, during the confusion, "Mister Dent [Two Face] tried to strangle himself." (p. 208)

Thus, both Moore and Gaiman make creative use of established Batman villains.