The little details in D&D’s rules are only as important as your group decides

Flanking: do creatures you control offer Flanking, as ‘allies’?

In D&D, there is no general rule that says only one spell can be cast on your turn

If you find concrete problems in one of our books, please let me know

Are the hit points and proficiencies of a class “class features” for the purposes of spells like Magic Jar and Shapechange?

When a non-visual area of effect is created, should it be clear where the boundaries are who didn’t cast it?

Do the size of Bigby’s hands change depending on the size of the creature that casts it?