Action Surge and Bladesinging Extra Attack Questions

[Ourian7491]

Seeing as how Action Surge gives us an additional Action, and Bladesinger's Extra Attack allows us to replace one of our attacks with a Cantrip of choice...

1) If I attack with my sword and a Cantrip, could I use my Action Surge and then attack with my sword and a cantrip again, effectively getting 2 weapon attacks and 2 Cantrip casts?

2) If I cast a spell, and then use Action Surge, could I then attack with my weapon and get a Cantrip cast?

3) Adding on to either scenario above, could I also add in a Bonus Action Spell into the equation, effectively getting 2 Attacks, 2 Cantrips and a Bonus Action spell in Scenario 1 and 1 Spell, 1 Attack, 1 Cantrip and 1 Bonus Action spell in Scenario 2?

[Keltest]

Seeing as how Action Surge gives us an additional Action, and Bladesinger's Extra Attack allows us to replace one of our attacks with a Cantrip of choice...

1) If I attack with my sword and a Cantrip, could I use my Action Surge and then attack with my sword and a cantrip again, effectively getting 2 weapon attacks and 2 Cantrip casts?

2) If I cast a spell, and then use Action Surge, could I then attack with my weapon and get a Cantrip cast?

3) Adding on to either scenario above, could I also add in a Bonus Action Spell into the equation, effectively getting 2 Attacks, 2 Cantrips and a Bonus Action spell in Scenario 1 and 1 Spell, 1 Attack, 1 Cantrip and 1 Bonus Action spell in Scenario 2?

One and two look correct to me, but three seems to run afoul of the rules about casting a leveled spell with an action and bonus action in the same turn when expanded from Scenario 2, unless the spell you use your Action to cast is also a cantrip.

[Quietus]

Different people interpret this differently. In both cases, your normal action will look identical, so I'll look only at the Haste interpretations.

Interpretation 1 :
- Here the emphasis is on the Attack action, and the limitation is intended to be read to disallow Extra Attack's additional attacks aspect. "One weapon attack only" is interpreted to mean "If you have Extra Attack, you do not get to make your additional attacks, just the one".

Interpretation 2 :
Here the emphasis goes further, and limits it not just to a single strike, but specifically to making an attack with your weapon. "One weapon attack only" is interpreted not just as the above, but also "You cannot shove, grapple, exchange this for a cantrip, or take any option that allows you to trade out your attack; you must make a singular attack with your weapon".

In both cases, it will not affect your ability to cast a spell as a bonus action, because you have not cast a leveled spell as part of your action. You'll have to talk to your DM to determine which of the above interpretations they follow.

[Witty Username]

3) Adding on to either scenario above, could I also add in a Bonus Action Spell into the equation, effectively getting 2 Attacks, 2 Cantrips and a Bonus Action spell in Scenario 1 and 1 Spell, 1 Attack, 1 Cantrip and 1 Bonus Action spell in Scenario 2?
You cannot use your action to cast spells other than cantrips if you cast a spell as a bonus action.
Strict reading, 3 is a no go.

Other than that,
Action surge gives you a Action, do what you can with Actions.

[Mastikator]

You can do #3 if you use your bonus action to cast a leveled spell first, then use your action to cast a cantrip (as a part of an attack action, or just normally). It's weird.

[Keravath]

The rule to consider is that if you cast any spell as a bonus action then the only other spells you can cast on your turn are cantrips (0-level spells) with a casting time of 1 action.

This means that all of your scenarios work except

"1 Spell, 1 Attack, 1 Cantrip and 1 Bonus Action spell in Scenario 2? "

If the spell is NOT a 0-level cantrip then you can not cast a bonus action spell on the same turn or if you cast a bonus action spell you can NOT cast a spell higher than a cantrip requiring 1 action to cast.

All the other scenarios work fine.

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In terms of an extra attack from Haste, I would say that a Bladesinger has to be able to use their extra attack feature in order to substitute a cantrip for one of the attacks. Since haste grants an Attack action that is limited to a single attack, the extra attack feature of a bladesinger would not apply.

[Chronos]

I'm not sure why anyone's talking about Haste, here... It doesn't look like the OP mentioned it?

Also note that bladesingers are a kind of wizard, and action surge is a fighter ability, so you'd need to be multiclassed to do what the OP describes.

And if you have Action Surge and have spellcasting from any source, then you can also just cast a regular (action, leveled) spell, and then Action Surge and cast another regular (action, leveled) spell. Unlike Haste, Action Surge doesn't put any restrictions at all on what you can do with the resulting action.