The big problem with twists like these…

If you know they’re coming, it sort of ruins the surprise. If the GM asks if it’s okay to have party betrayal (or if someone else asks and the GM says yes) then you’re constantly on the lookout for it - because why would they ask if it was irrelevant? Of course, nothing says the GM can’t ask an irrelevant question in the same manner they keep irrelevant minis next to their screen, but it’s something that’s usually frowned upon (what amounts to non-consensual PVP), so if it’s known to be ok, you’ll be looking out for it and then the twist won’t stick.

Of course, if you don’t know it’s coming, then it’s never a place your brain will go. You aren’t just going to accuse a character (and thus player) of working against the party because that’s a heavy accusation. It carries a lot of weight behind it since you’re only a few steps down from calling someone a problem player. Players often don’t have a good enough grasp on other players’ characters to notice behavioral shifts, and players often don’t have good enough acting skills to roleplay them correctly.

I’ve yet to hear a story where someone figured this kind of twist out before the reveal, and that doesn’t surprise me at all.

But by no longer utilizing poison against the party because of the monk, the monk has effectively made the entire party immune to poison by virtue of it no longer being present in encounters! Hah!

But seriously though, cutting out stuff you know the party will hard-counter is just going to make the party not feel as cool. A balance of both is important. Believe me, as the guy in the party who could cast Silence, I know; hard-countering every boss encounter kind of makes the boss feel lame instead of fun.

Not quite the same, but a Paladin in a campaign I was in once bought a Shield of Missile Attraction for cheap because the shopkeep thought it was cursed.

Is this… “Eliad Dais” fellow someone I should know?

I feel like I’ve seen a meme of this nature with the exact opposite take on this exact same frame.

I remember offhand it being 50 GP per level of the spell you want to cast, though I can’t say where in the PHB I read that.

It’s 3000 GP just for the material components, plus another 400 to pay the caster. At one gold piece a day (the amount a skilled artisan earns) it’d take 11.5 years to earn a clone with a poor lifestyle (2 SP per day).

So you’re living a poor lifestyle for basically half your professional life, just to earn the ability to repeat your professional life and spend another 11.5 years of it earning the ability to repeat your professional life just to spend 11.5 years of it earning the ability to… you get the idea. You’d also need to find a caster capable of casting an 8th level spell, which is rare.

Possible? Yes. Popular? I doubt it.

A clearer way to phrase it might be “there are no rules for the genre of fantasy”. An individual world needs self-contained rules, yes, but just because Tolkien’s Dwarves have beards regardless of gender doesn’t mean that your Dwarves need to be the same.

Wild magic Sorcerer: I do not control the Lobsters (they just kind of showed up)

You check the label and realize it actually says “Tenser’s floating Dikc”, but the salesman is already gone.

In my eyes, the Rule of Cool is best used as the opposite of the Air Bud Clause. (For those who don’t know; the “Air Bud Clause” refers to a rule in basketball that basically says “it’s not allowed just because there’s no rule against it”.) TTRPGs are imperfect systems, and you are going to run into a scenario that isn’t covered in the rules. Rule of Cool is best used here, rather than to bypass rules that do exist.

But also; some systems can be really crunchy, and a lot of the time it can be more fun for everyone involved if you just say “you know what, that’s cool, let’s do it” than to pause for five minutes to leaf through some rulebook (because seriously; you can’t always know the entire rulebook by heart) trying to determine if and why they can’t.

Of course, doing this too much is dangerous. Hence “in moderation”.