How about an item for Shadow of the Demon Lord
Mirror of Eternity
This concaved silvered disk reflects all behind it. If you stare deep into the disk, you can see deep into the universe. Sometimes, you don’t want to see what stares back.
As a triggered action, a character can stare into the disk. If they do so, for the next minute they gain 2 boons on all spell casting checks. At the end of that minute, the character must make a Will challenge roll. If they fail, the demon lord stares back, the mirror fades to black until the next dawn, and the character has 1 bane on all spell casting checks until they take a long rest.