Related to What do I know, when deciding whether to cast Counterspell?, except that my particular question isn't included in that question.

I've been thinking of ways to counter counterspell. Normally you can trick your opponent by casting low-level spells; the issue with this is that even though you burn their spell slots, you are potentially wasting actions. Burning enemy spell slots isn't usually very useful if the creatures you face tend to have all their resources at the beginning of a battle. Hence I figured the best way for me to counter counterspell is to cast low-level bonus-action spells.

But I had a thought:
Can a monster hold off on their reaction until your spellcasting has taken some time and they realize it isn't just a bonus action?

This goes both ways.
Should I be able to wait to use my counterspell until I know it isn't just a simple quickly cast spell?

  • \$\begingroup\$ Is the monster or the pc the one who is casting the counterspell? \$\endgroup\$
    – Akixkisu
    Feb 22, 2020 at 3:18
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    \$\begingroup\$ Monster was the intention. I'd prefer if I could waste a counter spell or two before he realized that actions were still coming his way (even though he was counterspelling). But as said it goes both ways, can I tell if it is for sure an action when I counterspell? Honestly I don't want the answer to be yes but I suppose it is up to the DM. Either way, I think having this question up here may help someone in the future. \$\endgroup\$
    – Dezvul
    Feb 22, 2020 at 3:19
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    \$\begingroup\$ My idea was actually in regards to a battle smith artificer. I was considering that I would be dishing out attacks after bonus action spells for like 2 turns, and they would realize that counterspelling may be wasted on me. Then I would be able to actually cast something if I wanted to. The issue is by taking this pattern, if a creature could wait until the spell was conclusively taking enough time to be a 'bigger' spell before counter spelling, any intelligent creature would do so; and just about any creature that can counter spell should have the intelligence to take this approach. \$\endgroup\$
    – Dezvul
    Feb 22, 2020 at 3:25
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    \$\begingroup\$ This doesn't answer your specific question, but for a good discussion of various other ways to prevent your spell from being countered, see these questions: Can I deny a counterspell by readying my spell behind full cover?, How can one spellcaster avoid complete lockdown via Counterspell against multiple other casters? \$\endgroup\$ Feb 22, 2020 at 4:13
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    \$\begingroup\$ @Medix2 I recognize there are plenty of bonus action spells that can stand up to full action spells. The artificer's banishing smite is a great example. So is quick spell for sorc (especially sunbeam). But I think it is still an effective tactic to use bonus action spells to make them question whether it is worth their counterspell. Especially if attacks come after that they could be shielding against. \$\endgroup\$
    – Dezvul
    Feb 22, 2020 at 4:29

1 Answer 1


RAW, you probably don't know

The trigger for counterspell is:

when you see a creature within 60 feet of you casting a spell

Nothing in the rules explicitly models the amount of time it takes to cast a spell as either an action or bonus action. It's not like an action takes 5 seconds and a bonus action takes 1 second or something like that. Mechanically, both actions and bonus actions happen "immediately"–they both are discrete events that can only be interrupted if an effect specifically says so (such as the trigger for counterspell). So while spells with a casting time of 1 bonus action are described as "especially swift", there is no explicit mechanical implication for this swiftness. Regardless of whether a spell's casting time is 1 action or 1 bonus action, there is only one "decision point" at which you can choose to counter that spell.

Your DM could rule otherwise (but probably shouldn't)

Despite the above, the fact remains that bonus action spells are described as "especially swift", and this logically represents an easily observable difference between such spells and spells with the "normal" casting time of 1 action. In 5e, the DM has broad latitude to "fill in the blanks" where rules aren't spelled out explicitly, so they could decide that you can observe a caster and determine that the spell they're casting has taken longer than what would be required for a bonus action casting time, before the spell's casting is complete, thus giving a window to still cast counterspell.

However, I would probably recommend against further complicating the casting of counterspell in this way. Adjudicating the timing of reactions that preempt their triggers is already tricky in practice, and the added complexity of this "two-phase timing window" for counterspell may just bog the game down every time a spell is cast, while ultimately having very little effect on the outcome of any encounter. That's not a favorable trade-off for having fun with the game.

  • \$\begingroup\$ +1, but I have 2 cents to give: As much as I like your answer, and find it preferable that a mage can't choose to counterspell only if the spell cast takes a full action (and not counterspell if it only takes a bonus action). I'd like to point out, though, that it wouldn't take much effort to put into practice (nor make it take longer to decide casting). The mage would either tell the DM "I counterspell only if the spell requires a full action," or "I counterspell regardless of action." If this is used regularly it would probably be shortened "I counterspell on action." \$\endgroup\$
    – Dezvul
    Feb 23, 2020 at 19:51
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    \$\begingroup\$ @Dezvul That's a good point with regard to the possibility of bogging down the game, but ultimately my main point is that if the intent was to have separate "windows of opportunity" to counter action and bonus action spells, that seems like the kind of thing that would be spelled out directly rather than left to be inferred from interactions between other rules. \$\endgroup\$ Feb 23, 2020 at 20:06
  • \$\begingroup\$ Which point I like, thank you. ;) \$\endgroup\$
    – Dezvul
    Feb 23, 2020 at 20:15

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