What happens while counter spelling Booming Blade 5e in dnd?
The description of 5e Booming Blade as of Tasha’s Cauldron:
“You brandish the weapon used at the spell of casting and make a melee attack with it from a single creature within 5 feet. On a hit, the target suffers the weapon assault’s expected results. It becomes sheathed in booming energy before the beginning of the next turn. In case the target willingly moves 5 ft or more before then, the target takes 1d8 thunder damage, and the spell ends.”
It might seem as if the melee attack and the cantrip. Although a part of the same action, they are two separate things. Your DM may rule since the melee attack could still undergo. Besides, the phrasing makes it look as though any other consequences (like whether it is a magic weapon) would still apply.
The attack was part of this spell’s effect. Counterspell means the spell had no impact, and the Cast a Spell action is “wasted” (from the point of view of the caster).
Narratively you can frame this by stating that the magical energies being summoned around the weapon suddenly dissipate. The caster, relying on these energies to steer the weapon, is abandoned. It is only standing there holding it, aware that the spell had been countered.
Confusion with Booming Blade in 5e dnd
No more cantrips cause as much confusion because of Booming Blade 5e and Green-Flame Blade. So it is good to double-check BOTH versions of the wording.
As exhibited in their first printing in Sword Coast Adventurer’s Guide, the important part of the charms here states the following.
“Being part of the action applied to cast the spell, you might make a melee attack with a weapon upon one creature within the range of a spell. Otherwise, the spell fails.”
And here is the relevant part of the spells from Tasha’s Cauldron of Everything:
“You brandish the weapon employed in the specific spellcasting and earn a melee attack with it against one creature within 5 feet.”
Employing SCAG wording, the assault still goes through. That would be more likely to utilize TCE wording. It is unless the effort is specifically set at the Sword Coast of Faerun. Therefore The attack does not go through counter spelling Booming Blade 5e.