Level Up & OSR Enthusiast
Is that something bone devils can normally do? Bad luck then.There's the dreaded "player knowledge" - one amusing example from a story hour, here, I think, many years ago, a PC is in a combat, and a hidden enemy has cast Wall of Ice three times, he concludes, confidently, that it must be a Sorcerer...
...turns out to be a Bone Devil, which, in defiance of any/all rules governing PCs, duplicates the 4th level spell at will.
Then there's character knowledge, which, in later eds, is covered by checks.