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Do the rules on counterspells essentially make it possible to always have your spells succeed?

(i.e...thus making high level one-on-one “cage match” wizarding duels simply a race to be first?)

In 5e, casting Counterspell requires a Reaction. Additionally, each character only gets one reaction.

Theoretically, that would mean that a wizard duel between two 20th level wizards could proceed like this:

  1. Mage A casts a spell (Power Word Kill) using their Action
  2. Mage B casts Counterspell using their Reaction
  3. Mage A casts Counterspell using their Reaction
  4. Mage B has no Reactions left so the original spell is cast.
  5. Mage B dies because the average wizard has less than 100hp.

Does this mean in mage-versus-mage combat, that a character casting a spell can essentially always ensure their spell gets cast as long as they have slots to cast counterspell at a level equal to their opponent’s?

Praxiteles
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    What does the spell identification rule in Xanathar's have to do with the rest of the question about Counterspell? I don't see the connection. – Bloodcinder Dec 17 '17 at 05:18
  • I don't think this is a duplicate, because the other question has a third mage. This is almost the same but has the same mage that cast the first spell also countering his counter (which may or may not be legal). I'm also unclear on how Xanthar's changes this situation. Overall, I think a clarifying edit will make this a good question. – Ifusaso Dec 17 '17 at 07:01
  • Part 2 of the referenced question specifies one enemy wizard. – keithcurtis Dec 17 '17 at 07:15
  • It's also answered here, not in the title, but in the example. https://rpg.stackexchange.com/questions/70236/can-you-perform-a-reaction-to-somebody-elses-reaction and here: https://rpg.stackexchange.com/questions/102158/can-a-caster-counterspell-a-counterspell-against-a-non-cantrip-spell-they-cast/102160#102160 – keithcurtis Dec 17 '17 at 07:24
  • I think that this question has potential if the Xanathar's bit is removed, and the enquiry about whether dueling counterspells makes wizard duels impossible is emphasized. – keithcurtis Dec 17 '17 at 07:34
  • I don't think it's a duplicate tho. Counterspelling a counterspell doesn't automatically allow you to finish your first spell in the same turn. Yes, the linked answer implies it does, but there wasn't any backup for that, the whole answer is focused at the "can you counterspell a counterspell" question. keithcurtis's answer clarifies the situation. – enkryptor Dec 17 '17 at 10:31
  • Is this question about 9th level spells or spells in general? When you cast Power Word Kill, you've already expend your 9th-level spell slot. If it is about spells in general, you could always cast a (counter)spell at higher level. – enkryptor Dec 17 '17 at 12:39
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    Based on the rewording, I have voted to re-open. Yes this particular nuance is answered elsewhere, but it is not asked elsewhere, and that's what users will search for. – keithcurtis Dec 18 '17 at 15:11

2 Answers2

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Yes, the action economy would work as you describe. Note that the ability to automatically counter requires the counterspell to be cast at a level equal to or higher than the spell being countered.

So if Mage #2 counterspell using a third level slot, they will need to make an Appropriate Ability Check if Mage #1's spell is say, cast using a 5th level slot. (per the description for counterspell, the DC equals 10 + the spell’s level.)

Similarly, Mage #2 could counter using a 7th level slot, and Mage #1 would have to use an equally powered counterspell or face an Ability check himself. So the counterings are not necessarily automatic.

Note, there is a special case at the highest levels of spellcasting. If two spellcasters are in opposition, and both can cast 9th level spells, then the countering mage can be certain that their counterspell will be successful, buy countering using a 9th level slot, even if the initiating wizard uses a 9th level spell. Countering at equal level slots is an automatic success. However, in this singular case the initiating spellcaster has no further 9th level slots to counter the counter, and must resort to an 8th level or lower slot, requiring an Ability Check.

For reference, the action economy of counterspell (and reactions to reactions in general) is clarified in the Compendium.

Can you cast a reaction spell on your turn? You sure can! Here’s a common way for it to happen: Cornelius the wizard is casting fireball on his turn, and his foe casts counterspell on him. Cornelius also has counterspell prepared, so he uses his reaction to cast it and break his foe’s counterspell before it can stop fireball.

In summary, neither casting of counterspell is necessarily automatic. You cannot ensure that your spells are uncounterable.

Note: this question was later edited to add the bit about "as long as they have slots to cast counterspell at a level equal to their opponent’s". I have left the first part of my answer intact for clarity and future reference by users seeking clarity, but added in the case where this would not be possible.

keithcurtis
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Yes, in a 1-on-1 situation like that, you are correct. If there are more mages involved, and thus more Counterspells to be cast, then it's more complicated.

Phil Boncer
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