Speaking of gas form, does it make much sense that while in gas form, you can still be physically restrained by some attacks? I'm not familiar with DnD so maybe it's an expected mechanics and i just don't know about it, but it did come to me as a surprise that during the final boss battle, the
were able to grab and restrain my characters in gas form. It felt counterintuitive to me but if that's the intended interaction then i have no issue with it.
This is one that folk have debated about on and off regularly over 5e's lifespan. Formally speaking, gaseous form does not make you immune to grapple and restrain - if it did, it would say so. It also doesn't give you free escapes from those conditions; again, if it did, it would say. Consider Freedom of Movement as a comparison; FoM specifically has a clause that lets you spend a small amount of movement to escape from non-magical grapples and restrains. Gaseous form hasn't got any such clause, so mechanically it does not. You should be able to escape from the grapple in all the normal ways (ability checks, teleports, force movements etc.), but even if you wanted to leverage the 'squeeze through small gaps' element of the spell, when you're grappled your speed is zero, so you can't move away in order to slip out.
How do we rationalise this, is the main question. The way I look at it is this: you are still yourself; you have a gas-like form and it's enough to make you able to squishy and deform through gaps, and to float and drift around, but you're still more or less your own shape, and you still have physical presence, which is why you can still be hurt. People can't pass swords through you; you're not actually a mist, you're a person with features similar to one. This means that someone can still grab your wrist or wrap their arms about your waist; you'll feel soft and cloud-like, perhaps, but you're still tangible enough for them to do so, and you still need to escape being grabbed like that as a single discrete entity with a body needs to do.
That's my reasoning to justify the RAW formalities of the spell at least.
