Can a PC cast additional spell using Action Surge?

Question

Can a spellcasting Fighter use the Action Surge ability to cast two spells (not cantrips) in one turn?

Answers to this question assume they can not, however, nothing in the rules explicitly restricts that. The only restriction described is the "bonus action" paragraph (PHB, page 202):

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.

But it is related to the bonus action, isn't it?

A follow-up question - what if the Fighter casts a Bonus Action spell with a cantrip, then takes the Action Surge, and then casts any "normal" (not a cantrip) spell? Will it contradict the "you can’t cast another spell during the same turn" part?

Answer 1

It would appear that Crawford's weighs in on the cantrip rule is only with relation to spells that are cast with the bonus action, this also made it into the Sage Advice Compendium.

Crawford confirms here.

Question: Can I misty step (bonus), fire bolt (action) and fireball (surge) on same turn? Or need action surge also be a cantrip?

Crawford: In that situation, the Action Surge spell would also need to be a cantrip

Crawford: The rule on bonus action spells pertains to your whole turn, not to a particular action (PH, 202).

PHB p202 Under Casting Times and Bonus Action

You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

Since Action Surge gives you a whole other action and not a another turn you can certainly cast another spell so long as you did not use a Bonus action spell.

The Sage Advice Compendium also provides clarification:

If you cast a spell, such as healing word, with a bonus action, you can cast another spell with your action, but that other spell must be a cantrip. Keep in mind that this particular limit is specific to spells that use a bonus action. For instance, if you cast a second spell using Action Surge, you aren’t limited to casting a cantrip with it.

Answer 2

If you have already cast a bonus action spell, you can only cast cantrips, Action Surge does not change this.

If you cast a full action spell, you can use Action Surge to cast another full action spell, but now you can not cast a bonus action spell.

Answer 3

Some people are misunderstanding Crawford's cross-comparison vis-a-vis Bonus Actions, Actions and Action Surge. If you cast a bonus action spell, your action spell as well as your action surge spell may only be cantrips (per the delineation for bonus action spells). What Crawford meant was that compared directly to an action spell (a "full" spell), action surge may be used to cast another "full" spell. That is not the case, however, if a bonus action spell was used at any point during the turn. (Note: this means that, for example, if you cast a full spell of any kind during your turn, you cannot take a bonus action spell (unless a specific indicator/spell descriptor specifically states otherwise), even with action surge. The only exception to this is — again as indicated by Crawford — that your Reaction can be used to cast a "full" spell even during your turn, which can (albeit rarely) occur when a mage casts counterspell against your "x" spell and you use your reaction to counterspell their counterspell.) Other than that, BA spell means no non-cantrip spells during your turn.

Answer 4

Yes, you can

From the "Casting Time" section of the Sage Advice Compendium, p. 12:

If you cast a spell, such as healing word, with a bonus action, you can cast another spell with your action, but that other spell must be a cantrip. Keep in mind that this particular limit is specific to spells that use a bonus action. For instance, if you cast a second spell using Action Surge, you aren’t limited to casting a cantrip with it.

Which explicitly means that you may cast a second spell using Action Surge and that it is not limited to a cantrip.

Answer 5

Seems to me the rules allow for these combinations during your TURN in a ROUND ...

• Action (Any Spell)
• Action (Any Spell) -> Action Surge (Any Spell?)
• Action (Cantrip) -> Bonus Spell
• Bonus Spell -> Action (Cantrip)
• Action (Cantrip) -> Action Surge (Cantrip) -> Bonus Spell
• Action (Cantrip) -> Bonus Spell -> Action Surge (Cantrip)
• Bonus Spell -> Action (Cantrip) -> Action Surge (Cantrip)

Casting a Bonus Spell will limit all Action Spells during your TURN to Cantrips (1 action casting), non-cantrip spells or cantrip (>1 action casting) will exclude the ability to use a bonus spell during your TURN, mattering which comes first.

There is also a rule that also states you cannot cast more than one spell during your TURN, except if that other spell is a cantrip. So the 2nd action of an action surge would be a cantrip.

The only exception to this would be if the bonus spell specifically stated it could be used before/after a non-cantrip/cantrip (>1 action casting) spell in the same TURN. This allows a specific spell's text to side step the rules.

Reactions can be used in the same ROUND as a bonus spell so long as they do not occur during your TURN unless it is specifically a Cantrip with a casting time of 1 action, keeping in mind 1 action is not equal to 1 reaction.

Reaction Examples: Counterspell (lvl3/1 reaction) cannot be used during your TURN with a Bonus Spell both because it is not a cantrip and also because it has a casting time of 1 reaction.

Hellish Rebuke (lvl1/1 reaction) can be used during the same ROUND as a Bonus Spell, if it is is triggered in response to being damaged outside your TURN. So if a creature on its TURN does damage to you, you can still use this spell as a reaction even if a Bonus Spell was cast on your TURN earlier in the same ROUND. If you incur this damage during your TURN, possibly by triggering a readied action and/or another creatures reaction, you would not be able to use this spell if you had already cast a Bonus Spell during your TURN, and if this reaction happens first, would not be able cast a Bonus Spell after it during your TURN.

TURN and ROUND generally clarifies how these rules should be handled, as well as the type and casting times of the spells.

NOTE: I've edited this to mark the Action (Any) > Action Surge (Any) option. There is a line in the Bonus Action section PH p 202 "You can't cast another spell during the same turn, except for a cantrip with a casting time of 1 action". The assumption is that this only relates to Bonus Action spells, but its wording is more broad and likely needs to be clarified by WOTC in future printings. There is some clarity to this by posts on Sage Advice hosted by wizards which suggests Action surge should allow any level spell be cast as the 2nd action.

Answer 6

Action surge grants an extra standard action and a possible bonus action. This extra action is not considered an extra turn, but additional action(s) allowed in the same turn.

This, as written, should give you free reign of these actions to do as you please, so long as you meet the requirements to do said actions. If a sorcerer/fighter casts fireball with quicken spell, it makes it as fast as a bonus action still leaving a standard action. A fireball can be cast with this standard since it is an instantaneous action. Now seeing as how a full set of actions have been taken, action surge can be activated to grant an additional standard action and (keyword here) a possible (also a keyword) bonus action. So with these additional actions it is very possible to quicken spell another spell into a bonus action and still cast another standard spell.

This is how it goes based on how the wording is placed. As I stated, there are no RAW restriction on what a player can or cannot do with these actions.