Role-playing Games Stack Exchange is a question and answer site for gamemasters and players of tabletop, paper-and-pencil role-playing games. It only takes a minute to sign up.
Sign up to join this community
Anybody can ask a question
Anybody can answer
The best answers are voted up and rise to the top
The description of the dread helm says (Xanathar’s Guide to Everything, p. 137):
This fearsome steel helm makes your eyes glow red while you wear it.
I am currently playing a character that ritually cuts out the eyes of enemies we kill. Our group had the idea of what would happen if he started attaching those eyes to the dread helm he’s wearing.
If additional eyes were attached to the dread helm, would it make those glow red as well? Or only the wearer’s own eyes?
The helm makes your eyes glow; somebody else’s eyes are not your eyes
Strictly speaking, whether or not somebody else’s eyes that you’ve effectively stolen count as your own eyes is going to be up to the GM. But I believe the extreme majority of people would interpret this as meaning your very own eyes; the ones that are (hopefully) inside your own head.
Rule of Fun/Cool
However, if I were the GM I would rule that all of them turn red because that is just plain cool and it is the type of fun and primarily cosmetic change that I encourage my players to seek out.
Only the eyes in your body count
Whether additional eyes glow depends on how you interpret “your” in the sentence.
DnD was written using common language. Most people when they read “makes your eyes glow red while you wear it” wouldn’t think that it could be used for interplanar communication. If the helm was intended to refer to eyes that belong to you in a capitalistic sense then it would have said so clearly. Since it didn’t we can understand that “your eyes” only refers to your bodily eyes.
With common language things only do what they obviously say they do.