A great Adams cover on Batman 221 (May 1970), although the story it refers to is not nearly as powerful.
Robbins, Novick and Giordano have Bruce Wayne in Germany, being requested by the authorities there to determine if there is any connection between a bio-tech company, located in Fledermaus Castle (Bat Castle), and animals becoming violent killers for no apparent reason.
Of course, there is a connection, with the Kramm family, who run the company, working on a formula to make make killer animals, some of which got into the water supply, affecting animals outside the complex.
When the killers bats in the castle fail to kill Batman, the daughter of the old Nazi who runs the company injects her husband with the formula, sending him to kill Batman. He fails.
The second story in the issue, by Friedrich, Novick and Giordano, is the reason I included this issue. It begins as a story about fires breaking out across Gotham, and appears to be a tale about an arsonist.
The fires prove to have a supernatural origin, an idol that a soldier brought back from Vietnam.
Batman throws the idol out the window and shatters it, which end the fires.
The closing narration states that Batman’s purpose is to deal with “supernatural violence.” Around this time, horror comics were far more popular than super-hero ones, which explains why the cover looks like something out of a horror movie, and the supernatural bent to the tale.