As a Level 6 Bladesinger Wizard, can you use the extra action granted by the spell Haste to cast a Cantrip? What if that Cantrip has you make a weapon attack as part of the Cantrip, such as Green-flame Blade or Booming Blade?

You take the Attack action with Haste, then Extra Attack triggers when you take the Attack action which allows you to cast a cantrip in place of one attack. But haste has in parenthesis (one weapon attack only), but you can satisfy this by making one weapon attack as part of the cantrip, as Green-flame Blade or Booming Blade specifically have you make a weapon attack.

Haste only seems to care that you satisfy:

A. Take Attack action (you do).

B. Make one weapon attack only as part of it (you do).

It doesn't have any specific language about the means of how that ends up happening or if a cantrip gets involved in some way.

Further, was the parentheses part of Haste actually intended to limit the attack to "weapon" attacks only, such as preventing a shove or a grapple, or was that just an oversight by the designers?


Choose a willing creature that you can see within range. Until the spell ends, the target's speed is doubled, it gains a +2 bonus to AC, it has advantage on Dexterity saving throws, and it gains an additional action on each of its turns. That action can be used only to take the Attack (one weapon attack only), Dash, Disengage, Hide, or Use an Object action.

When the spell ends, the target can't move or take actions until after its next turn, as a wave of lethargy sweeps over it.

Bladsinger's L6 Extra Attack feature:

Starting at 6th level, you can attack twice, instead of once, whenever you take the Attack action on your turn. Moreover, you can cast one of your cantrips in place of one of those attacks.

Booming Blade:

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects and then becomes sheathed in booming energy until the start of your next turn. If the target willingly moves 5 feet or more before then, the target takes 1d8 thunder damage, and the spell ends.

Green-Flame Blade:

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects, and you can cause green fire to leap from the target to a different creature of your choice that you can see within 5 feet of it. The second creature takes fire damage equal to your spellcasting ability modifier.

Emphasis of relevant sentences mine in Bold

  • 3
    \$\begingroup\$ Hey Fey. Please don't repost a question that has been closed and then deleted the original as it will just get closed again. Instead edit your original post to address any concerns mentioned in either the close banner or in comments on that post. I know there haven't been any comments on the original Q other than a 'welcome' and I'm aware you have been editing the original post so I just want to mention you're not in trouble or anything. What I will say is that if your question isn't answered by the duplicate then it might help to include a passage about why it doesn't answer your question. \$\endgroup\$ Dec 23, 2021 at 3:26
  • \$\begingroup\$ @PurpleMonkey I did edit it. The original one was blocked for being a duplicate, but the only question asked like it doesn't address the green-flame blade/booming blade part that goes into a weapon attack. I hadn't included that part in my original title. This one does. and then elaborates more. There's no other question that covers this. It told me to edit it. Did that nothing happened for a day, also said to try asking another question. So did that. \$\endgroup\$
    – Fey Long
    Dec 23, 2021 at 3:30
  • \$\begingroup\$ Yeah, the close banners aren't always the best help, unfortunately, and things fall by the wayside around this time of year. I reckon this question is different enough to warrant reopening but I would suggest deleting this post then undeleting your original post and adding in a small passage stating that, while similar, "How does the Bladesinging wizard's Extra Attack feature interact with the additional Attack action from the Haste spell?" doesn't address Green-flame Blade or Booming Blade. \$\endgroup\$ Dec 23, 2021 at 3:43
  • \$\begingroup\$ Then we can get it reopened for you. It may seem a bit silly to go about it that way but I think it works out better for background processes, though I could be completely wrong and it may not even matter. \$\endgroup\$ Dec 23, 2021 at 3:43
  • \$\begingroup\$ @PurpleMonkey I tried, Tomas Markov says the other questions answer it as they cover all cantrips and we couldn't ask about each and every cantrip specifically. I don't think he understands. \$\endgroup\$
    – Fey Long
    Dec 23, 2021 at 8:07


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