The improvisation rules say that the DM should use the existing rules as a guideline for what is or is-not possible, and how to model them. That is both the letter and the intent of the rule. Nobody is arguing with that.
The issue at hand is that this particular ruling - this specific mechanic for performing this action - is completely out of line with what is otherwise possible within the rules that are codified. It is an order of magnitude more powerful than either shoving or grappling. A reasonable person would not read the rules in the book, and then assume that they could make an opposed Athletics check to gag a spellcaster during combat.
I understand your line of thought. But I digress in your conclussion: gagging someone is specifically quoted as a way to impede verbal components,
and verbal components are rules. And any attempt of gagging someone would quickly lead to a combat, in some way or another. And it is mostly relevant in combat, not outside it. And it is an order of magnitude more powerful under specific circumstances: it only impedes casting with verbal components, but there are multiple actions that said caster could take,
including casting spells without verbal components. And there are spells and actions a caster could do to invalidate this very easily: spells like
freedom of movement that renders your caster immune to this, and spells like
misty step, that allow you to escape. And there are more than one physical approach: Athletics or Acrobatics. Furthermore, why do even include verbal components if they aren't relevant?
The logical ruling here would be that the DM says such an action is impossible, exactly the same as if the wizard player wanted to use their knowledge of magical weather to trap the fighter in an ethereal tornado. It doesn't matter if the fighter could theoretically escape by making an opposed Arcana check. It would invalidate the game that everyone else signed up to play, the same as if you let someone bypass hit points by taking a 'slit throat' action. Any action that is egregiously out of line with existing actions should be impossible.
The fact is, there are spells that do something like that, and worse.
Hold Person, that paralyzes and imposes a Saving Throw no martial has.
Forcecage.
Control Water to create a wave to knock a fighter.
Tsunami, for a more gruesome way to do the same. And, as I've said earlier, this is in the same order of magnitude than a
disarm. It doesn't disable a caster in every possible way, such as an ethereal tornado or a hold person. It just prevents certain spells with verbal components. Furthermore, it isn't
impossible: it is a valid approach, using the existing rules. You could rule it otherwise, [MENTION=6775031]Saelorn[/MENTION], and increase the difficulty accordingly. I'm not complaining on that. This mechanic, specifically, could be flawed by being too easy, but not by intent. If the rogue would try to use its expertise in
Sleight of Hands to steal the material components of a spell, such as a crystal that acts as an arcane focus, you would say the same? That it is an abuse? I'm taking advantage of an already existant ruleset (spells components), and using them in advantage.
As for your specific example, Arcana checks aren't used for spellcasting, spellcasting has its own rules. Managing ethereal storms would fall under spellcasting, unless you are in the ethereal plane (in which I would allow an Arcana check to manage the storm against the martial). Even more, I could allow a Very Difficult arcana check, then expend a spell slot, and then renounce to half the movement and both hands to do something like what you said without being in the ethereal plane (I usually allow improvising with existing spells with arcana checks).
But Athletics are used for attacks, I've specifically quoted when. And they can function as a model of how to do something like that. That's why I've proposed to be two successive Athletics checks, with both free hands as an option,
and at disadvantage. Choking someone isn't something fantastical, implausible or in the order of the supernatural, it is a very common way to fight; grabbing someone and shut the mouth is also something very common, both in fiction and reality. Saying that it is
impossible... it is limiting a great deal the fighters, denying things that they really aren't all that difficult, while pumping the casters by ignoring the components rules.
Of course, as I've said, if you come with a better way to do it, one you think it is more balanced, I'll be glad to hear them.
