Circlet of Human Perfection vs Book of Vile Darkness

Question

I am wondering about the interaction between the Circlet and Book; specifically, whether the Circlet masks the Book's disfigurement.

The rules for Book of Vile Darkness state:

Mark of Darkness. After you spend the requisite amount of time reading and studying the book, you acquire a physical disfigurement as a hideous sign of your devotion to vile darkness. An evil rune might appear on your face, your eyes might become glossy black, or horns might sprout from your forehead. Or you might become wizened and hideous, lose all facial features, gain a forked tongue, or some other feature the DM chooses. The mark of darkness grants you advantage on Charisma (Persuasion) checks made to interact with evil creatures and Charisma (Intimidation) checks made to interact with non-evil creatures.

The Circlet of Human Perfection Reads:

The Circlet of Human Perfection transforms its attuned wearer into an attractive human of average height and weight. The circlet chooses the physical characteristics of the form, such as age, gender, skin color, hair color, and voice. Except for size, the wearer's statistics and racial traits don't change, nor do items worn or carried by the wearer. Removing the circlet ends the effect.

Would the Circlet override the disfigurement?

Answer 1

There's nothing preventing the Circlet from overriding Mark of Darkness

Nothing in the description of Mark of Darkness prevents it from being hidden in any way. A character afflicted with the Mark could just as easily cast Disguise Self or Alter Self to mask the disfigurement. Heck, depending on the mark, they could paint over it with a disguise kit. I'll add that disguising one's hideous appearance with magic is a tried and true strategy of villains the world over. This seems narratively appropriate.

Of course, since the Advantage on Persuasion and Intimidation checks comes directly from the visible disfigurement, concealing the mark would also remove that benefit.

However...

While there's nothing stopping the Circlet from concealing the mark of darkness, and doing so wouldn't be unbalanced according to the rules since it's actually removing a benefit while only duplicating a second-level spell, there is nothing in the Circlet's description that explicitly guarantees the mark will be removed. After all,

The circlet chooses the physical characteristics of the form.

Beauty is a social construct. Who's to say that a magical headband shares society's general concept of beauty? Maybe it thinks glossy black eyes are incredibly beautiful. The fact that the item has control over the exact nature of the form is what balances the Circlet against a regular casting of Alter Self, which costs a spell slot, requires concentration, and has a limited duration.

So, ultimately, the DM can always make an argument that the Circlet chooses not to hide the wearer's evil disfigurement, or only partially hides it, or replaces it with a different disfigurement. But doing so isn't required by the rules, and the Circlet's effect is already balanced.