Wondrous Item, rare
You can take a Magic action to blow the horn, which emits a thunderous blast in a 30-foot Cone that is audible out to 600 feet. Each creature in the Cone makes a DC 15 Constitution saving throw. On a failed save, a creature takes 5d8 Thunder damage and has the Deafened condition for 1 minute. On a successful save, a creature takes half as much damage only. Glass or crystal objects in the Cone that aren’t being worn or carried take 10d8 Thunder damage.
Each use of the horn’s magic has a 20 percent chance of causing the horn to explode. The explosion deals 10d6 Force damage to the user and destroys the horn.
Notes: Damage: Thunder
I dislike the new wording from 2014. On a successful save, the old version says "... and isn't Deafened" and the new version says "... only"
So, are they still deafened on a successful save as in 2014? Just polled my group, and they're split down the middle.
The placement of the "only" at the end suggests no, and that the function remains unchanged from 2014. Had it been placed before, ie "... and only takes only half damage", I'd say yes, it is a change in functionality and the creature is still Deafened. But, the very fact that they made the change, suggests that it now behaves differently, and was an intentional change. However, it's equally possible (and likely) that the change was for brevity and "clarity" (double-quotes intended, as this is hardly "clear").
So which is it? RAW, I'd say it is unchanged. RAI? Who the f#@& knows? This could have simply been a space saving change with no change of functionality, intentional or otherwise, as they've made elsewhere in countless other places. Or, it could have been intentional change in functionality, in which case I'd suggest that the "only" is in the wrong place. Which is it? I have my opinion (no change in functionality), but it's only that: an OPINION. It differs from players, because this is no longer DEFINITIVE!
How to avoid this crap? DO NOT MAKE THE CHANGE!!!
This is bad design. The rules are not read in a vacuum, and it's bad design to assume that they are. People will try to glean context based on how it changed over previous editions, especially when it has been made ABUNDANTLY CLEAR that this isn't a "new edition". The result? It leads to bickering and rules lawyering, all to save a few words.
It should say, either: "...and is still Deafened" or "...and isn't Deafened."
Period. Full stop.
3 of 4 words to clear this up and avoid the misinterpreations, bickering and rules lawyering. That's all it takes.
Bad. Design.
I get that the book is long, but this, and dozens of others of examples like it, was not the place to save space.
It's less clear. Not more.
That "..****y" language on successful saves is a very commonly used phrase in magic item descriptions. It means that the only thing that happens is half damage, and none of the other effects on a failed save apply.
Oh look, a logical person!