mechanic replacement

[Seraphor]

You can partially thank the English team for this — which, as usual, mangled it into something needlessly more convoluted than it was in other languages.

English:
My cup runneth over with fire and lightning!

JP:
雷属性、火属性エーテル充填……
バリアチェンジ！

Lightning and fire ether are filled up...
...Barrier change!


...Why is the English in faux old English for some random Garlean guy engineered in a laboratory?

Why is it using this strange and ambiguous phrase? It's just confusing at a glance — what cup? What is he talking about? What am I supposed to interpret from this? It's just such 14-year-old's Tumblr / DeviantArt "You know, I'm something of an author myself" pretentious fake depth.

And it doesn't even mention the barrier part.

That's not the problem.
I can't see how this difference in dialogue changes things, you're still only picking out the key words fire and lightning, and you still have no reference for whether you're supposed to be standing in fire/lightning, or avoiding them, besides trial and error.

The fact that the only indication came in the form of dialogue, and wasn't included in either the action name or anything visual, is what caused people to miss it.
I mentally block out all non-voiced dialogue when I'm in battle (it doesn't help that the font is very low weight on a beige speech bubble) and I don't have it displayed in chat log either because it fills it up with spam.
This is the only fight I can think of in the entire game where this is the case, every other attack from every other fight (baring an odd exception that I may have forgotten and must be less impactful) has an indication that uses battle mechanics, i.e. action names (spell charging or flying text when used), player indicators (stacks, TB's etc.), ground effects (AOEs), or boss effects (e.g. WoL's in/out indicators).
Larboard/Starboard was better than this.

[Rongway]

The fact that the only indication came in the form of dialogue, and wasn't included in either the action name or anything visual, is what caused people to miss it.

No. Hard no. There was a long cast bar for an action called "Barrier Shift". Then the boss acquired an elemental buff. There were multiple indicators for what to do. If people couldn't connect that to their damage being reflected when they didn't have the right element...

[Seraphor]

No. Hard no. There was a long cast bar for an action called "Barrier Shift". Then the boss acquired an elemental buff. There were multiple indicators for what to do. If people couldn't connect that to their damage being reflected when they didn't have the right element...

Well as I previously said. I get this dungeon maybe once every six months. So I miss those buffs every time, and by the time I notice them, the fight is over and it'll be another six months before I need to think about it again.

Admittedly I don't tend to look at enemy buffs a whole lot outside of EX/Savage, as they're not usually uniquely integral to the fight in casual content, and you can't 'hover over them' to see what they are on controller.

The action name doesn't tell you anything, other than he's doing a thing. It's changing his elements sure, but does it change them to elements you're supposed to avoid or stand in?