Is the spell combo Booming Blade into a quickened Thunderwave legal? [duplicate]

Question

I'm sure this topic has been beaten to death, but I can't seem to find the answer I'm looking for. That being said, maybe I'm just not seeing the answer for what it is and I just want to feel special by having my specific question answered. In either case, if the question doesn't say it all, basically level 3 sorcerers have access to both Thunderwave (1st level spell) and Booming Blade (cantrip.) Bonus action spells don't let you cast anything that isn't a cantrip afterwards so:

Healing Word into Firebolt in one turn is allowed but, Shillelagh into Cure Wound in one turn is not allowed.

That means Bonus Action Leveled Spell casted first, then Action Cantrip in one turn is ok to do,but Bonus Action Cantrip casted first, then Action Leveled Spell in one turn is not ok to do.

I ask about case 3, Action Cantrip casted first, then Bonus Action Leveled Spell in one turn, is this ok?

No question I've seen specifically says whether or not casting a 1 action cantrip disqualifies your character from casting 1 bonus action, level 1+ spell in cases where action order matters.

If the quickened Thunderwave comes first, then the monster will be too far away to hit it with Booming Blade: so, is the Thunderwave allowed to come second?

Answer 1

Bonus Action

A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven’t already taken a bonus action this turn. You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

Above are the rules for casting a spell as a bonus action. It sets up a few conditions:

• You may not use another bonus action in the same turn that you cast a spell as a bonus action.

• You can't cast another spell during the same turn, unless it is a cantrip with a casting time of one action.

Your scenario meets all the criteria of the rules. Booming blade is a cantrip with a casting time of one action. That makes it a legal cast. And there are no rules specifying the order you cast the spells in.

Where things get confusing is that you can't reverse the action types of the two spells. Even though bonus-Booming Blade action-Thunderwave has the same net outcome as action-Booming Blade bonus-Thunderwave.

This quirk is due to the rules specifying that the 1 action spell must be a cantrip instead of a more general rule that one of the spells cast must be a cantrip.

Answer 2

You can do that; Booming Blade damage won't trigger on your turn

Your case 3 works, per the three linked questions that were called out as duplicates.

Does order matter when casting a cantrip with a casting time of a bonus action and another spell?

Casting multiple spells in a single round

Which uses of Bonus-Action spellcasting are legal?

These are based on the rule about casting spells with a bonus action.

Bonus Action

A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven’t already taken a bonus action this turn. You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action. (Basic Rules, p. 83)

A problem arises when you take an action (booming blade) and the damage trigger is the movement of your target. Forced movement won't trigger Booming Blade. Thunderwave's pushback mechanic is forced movement. Per a comment you made previously, you are trying to get the enemy to "come at you" - which would trigger the booming blade as they are moving voluntarily, which works.

That trigger will happen on their turn rather than on your turn, if the DM/Monster Player chooses to "come at you" after you push a few back.