How could you do this to AST?

[RyuDragnier]

They won't though, due to the very way some effects are coded in this game ("if dmg <> 0 then debuff" wouldn't even surprise me lol). This would allow a lot more cheeses on strats.
See E10S tourniquet shield cheese and imagine that on a lot more mechanics. Or how some tanks can cheese with invuln due to taking 0 damage (PLD, GNB) and others can't because they take damage so the debuff anyway. And imagine that stacking shields could sometimes work as those invuln with sufficient mitigation (reprisal, addle etc...)

The thing is, they already confirmed there's going to be battle system adjustments, including a stat squish (since apparently the high numbers are putting a major strain on the system). I wouldn't be surprised if they made it so the debuff kicks in regardless if barriers are there (not invulns), thus bypassing this particular problem.