@nskid11 RAW, Booming Blade doesn’t now allow an offhand weapon attack (two-weapon fighting) because it’s not an Attack Action? That's correct.
— Jeremy Crawford (@JeremyECrawford) December 6, 2016
@nskid11 RAW, Booming Blade doesn’t now allow an offhand weapon attack (two-weapon fighting) because it’s not an Attack Action? That's correct.
— Jeremy Crawford (@JeremyECrawford) December 6, 2016
I disagree with this. When you cast booming blade you get your weapon damage too right? If so, then the movement with the weapon is somatic it’s an actual attack.
It is an attack since it uses an attack roll, but it does not use the Attack action, it uses the Cast a Spell action. Like many spells, the spell involves an attack roll, but it is still cast using the Cast a Spell action, like all spells that take an action to cast.
These are simply how the game terms are defined. You may choose to houserule, of course, but the RAW is clear — there is no Attack action used. Some features key off you making an attack. Some features, like Two Weapon Fighting, key off you taking the Attack action. This is quite deliberate, and requires the DM to understand the distinction between making an attack, which can happen in many contexts (some of them outside the Attack action and some not even on your turn), and taking the Attack action, which can only happen using your action on your turn.