Anathema

Silver is anathema to werewolves, so hopefully Feiya and Merisiel remembered to bring some.

Some creatures, particularly outsiders, have specific vulnerabilities known as anathemas. Commonly known anathemas include silver's effects against lycanthropes and devils; sunlight's effects on vampires; and cold iron's effects against daemons, demons, and fey.

Anathematic substances are often incorporated into weapons designed to harm outsiders, and magic circles used to bind or ward against them.