Legendary Action in the Monster Manual says:

A legendary creature can take a certain number of special actions — called legendary actions — outside its turn. Only one legendary action option can be used at a time and only at the end of another creature’s turn. A legendary creature regains spent legendary actions at the start of its turn. It can forgo using them, and it can’t use them while incapacitated or otherwise unable to take actions. If surprised, it can’t use them until after its first turn in the combat.

(emphasis mine)

A creature I'm preparing to run has Shield and Counterspell as at-will spells, and it can cast at-will spells as legendary actions. Would this allow the creature to break the 1 reaction per round rule and cast both, or (if necessary since it has 3 legendary actions) even 1 shield and 2 counterspells?

I'm including the name here but hiding it due to spoilers:

Acererak, Tomb of Anhilation.


2 Answers 2


A Legendary action is not a reaction therefore it would not affect the reaction economy.


Counterspell would not work as a Legendary Action, Shield would work.

There is similarity here with the wording of Staff of Defense, it lets you cast shield as an action, in which it lets you cast a spell outside of it's normal casting time of, in Shield's cast, 1 Reaction. Counterspell does nothing unless it is targeting a creature that is casting a spell. A player casts a spell, the spell does it's effect, their turn ends...the creature with Legendary Actions can't counter a spell that's already gone!

You would also be able to have the creature in question use it's Reaction to cast a spell, say Counterspell, and still cast a spell at the end of it's turn as a Legendary Action because casting as a Legendary Action is not a reaction, it is a Legendary Action.

Acererak can cast one of his at will spells as a Legendary Action. However, it doesn't say you can cast them whenever you want, just as a Legendary Action. This means he wouldn't be able to cast Counterspell as it requires the target of a creature casting a spell and players will not be casting at the end of their turns, usually. (I can't think of how this situation would happen)

This leaves a strange spot for Shield though but I'll reemphasize my point of Staff of Defense saying you can use your action to cast shield, with how the Legendary Action says you can cast the spell. This means he would be able to benefit from Shield until the start of his next turn. This would not take up his reaction as he is not using his reaction to Shield, he is using his Legendary action. This brings up a situation of him casting another full level spell though. With how the rules on spells only includes being able to cast a cantrip after bonus actioning a spell, Bad Guy would be able to cast Counterspell on another player's turn as a Reaction, per the normal spellcasting rules, and then be able to Shield himself as his Legendary Action at the end of the Player's turn.

Here's a scenario

Player 1 Casts fireball or some other spell.

In Reaction, The Bad Guy Counters the spell.

Player 1's turn ends.

Bad Guy uses his Legendary Action to cast Shield, without requiring someone to attack him because his Legendary Action allows him to cast it anyway, and this uses up one Legendary Action. Bad Guy is out of Reactions and will not be able to do another one till the start of his next turn.

Player 2 casts a spell at Bad Guy and he is forced to make his saving throw or use Legendary Resistance as he is still without a Reaction.

Bad Guy casts Ray of Sickness targeting Player 2 using a Legendary Action

Bad Guy takes his turn and gets his Reaction back.

And so the cycle continues.

My thoughts on non 1 Action spells being used as Legendary Actions:

Legendary Actions are 'Special actions' as they are used at the end of another player's turn. I'm going with the assumption that Legendary Actions are not actually just 'an Action' but their own independent thing. This could be incorrect though with the wording of 'Special actions' and not 'it's just an Action you take on another turn' I'm going with my interpretation.

With that in mind I'd say that because that it is a "Legendary Action" if you weren't able to cast Reaction spells you wouldn't be able to cast 'any' spell. How would one be able to cast a spell with a casting time of 1 Action if you are using it as a Legendary Action? It has a casting time of 1 Action not 1 Legendary Action!

Obviously this is not the case as some creatures can spell cast as a Legendary Action. It would apply to all spells that have a valid target, such as Shield.

Big Bad can use his Legendary Action to cast an at will spell, of which included is Shield which has a normal casting time of 1 Reaction. Staff of Defense lets you use an Action to cast Shield, normal casting time of 1 Reaction. If the latter works so should the former. I feel this is a case of Specific, the ability to use an Action or Legendary Action to cast spells, versus General, casting spells at their normal casting times.

Even if Legendary Actions are just a regular Action that is at a strange time it is clear that the Specific case, as in the case of Staff of Defense, overrules the normal casting rules and that it should be fine either way. Otherwise you wouldn't be able to cast Shield as an Action using Staff of Defense.

In a late summary of the final pieces here: A player could use his Action to cast Shield using Staff of Defense. The Big Bad could use his Legendary Action to cast Shield using his Legendary Action ability.

  • 2
    \$\begingroup\$ Note, that Rituals are cast over multiple rounds. So, Counterspell could be used as a Legendary Action against those. \$\endgroup\$ May 18, 2022 at 23:24
  • \$\begingroup\$ @ProphetZarquon Old reply, but very nice find. \$\endgroup\$
    – Jihelu
    Jul 14, 2022 at 16:58
  • 1
    \$\begingroup\$ I had a similar concern come up, regarding the timing of Legendary Actions. Old answers never die, they just become arcane! \$\endgroup\$ Jul 19, 2022 at 17:48
  • 1
    \$\begingroup\$ @ProphetZarquon Glad you find some use even with my older answers! I admit I should probably reward it just a bit, but on retrospect I think it's still the correct solution. I think I could have explained it just a smidgen better though. \$\endgroup\$
    – Jihelu
    Aug 21, 2022 at 1:37
  • \$\begingroup\$ Casting a spell with a casting time longer than one action isn't just applicable to ritual spells. It's unlikely a player would do it midcombat, but if someone were to try to cast tiny hut, (or were in the middle of casting it when combat started and wanted to attempt to complete the spell,) or another longer casting time spell a Legendary Action counterspell might be just the thing to disrupt it. \$\endgroup\$ Mar 21, 2023 at 17:15

A legendary action is not a reaction.

The different types of actions are not interchangeable. For example, Jeremy Crawford has stated that you cannot use an action to use something as a bonus action.

Shield and Counterspell don't happen at the end of turns

Even if you could use a reaction as a legendary action, legendary actions only take place at the end of another creature's turn, whereas shield and counterspell need to be used to interrupt another creature's turn. Shield's casting time states,

Casting Time: 1 reaction, which you take when you are hit by an attack or targeted by the magic missile spell

Which means that, barring special circumstances, it can only be cast when you're hit by an attack.

For example, a creature can make an attack and then move (PHB 190). Therefore, the moment where a creature is attacking or casting a spell is not the end of its turn. The end of a creature's turn is when the creature has completed everything that it will do that turn, which means it's too late to cast Shield and Counterspell.

  • 1
    \$\begingroup\$ I believe Shield would work as a Legendary Action for the same reason it works for Staff of Defense. Counterspell, however, would not. \$\endgroup\$
    – Jihelu
    Jan 14, 2018 at 2:21
  • \$\begingroup\$ @Jihelu Legendary Actions and the Staff of Defense work very differently. \$\endgroup\$ Jan 14, 2018 at 23:10
  • 4
    \$\begingroup\$ @SevenSidedDie Yes but it does give us the circumstance that something that allows a spell to be cast allow it to be cast. Normally shield can not be cast as an action but Staff of Defense says it can be. Legendary actions are 'special actions' and not even an 'action'. Going by the logic of 'You can only cast a spell normally' so 'One action' or 'reaction', that would mean you couldn't even cast spells as a Legendary Action because it has a cast time of 1 action, not 1 legendary action. Or atleast that's how I've interpreted it. \$\endgroup\$
    – Jihelu
    Jan 15, 2018 at 4:14
  • \$\begingroup\$ @Jihelu Oh, I see what you mean. Nevermind! :) \$\endgroup\$ Jan 15, 2018 at 5:22

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