Counterspelled Booming Blade

[KorvinStarmast]

"Rulings not Rules" is just another way to say Rules as Guidelines,

Captain Jack Sparrow, and I, thank you.

And that's ok too, but heating elements glow, so my Wall of Toasting emits light, damn it.

Is that an Artificer spell?

Hmm... casting a spell without a spell slot, nor a magic item designed for it?

I guess Chapter 10 and Chapter 11 don't exist, nor do the Spell Casting Features in each class description.

Now we just need to settle the argument of what Int (Arcana) DC I need to hit on my fifth level samurai fighter to cast Fireball.

Nope. Check Chapter 7. You only make an ability check if something is possible. Long jumping to the moon is not possible; there is no DC to set

Mind you, if the Samurai has a scroll that might be an interesting avenue to explore via an INT(Arcana) check...depends.
I'd offer disadvantage if allowed, but, there's a problem imbedded with that from the get go.
If I am a Cleric and I try to read a Wizard scroll, I can't understand it.
Not sure how a Fighter would fare any better.
See Chapter 10 and Chapter 11, and also see DMG.

Fair point.

The fireball one is not a fair point.