Readying to cast a spell

[Grayhawk]

Can you use the ready action with the following trigger:

'If he cast's a spell, I'll cast a spell, based on a Spellcraft check (free action).'

Or do you need to state whether you're readying to disrupt, to counterspell or some other particular spell use?

Example: Is it possible to ready the casting of a spell against a spellcaster casting Magic Missile, and if you recognize it with you spellcraft check choose between countering it with a Magic Missile of your own, trying to counter it with Dispel Magic, put up a Shield or some other defensive spell, or casting a Dimension Door to get out of the way?

If your readied action doesn't disrupt the original caster's spell, may he choose to do something else based on your triggered action?

 

[James McMurray]

It depends on how you view the phrase "can ready a standard action."

"Cast a spell" is a standard action, albeit a very broad one.

"Cast magic missile targetting those two guys" is also a standard action, but much more constrained.

Would you allow a fighter to ready an attack, and then use the attack as a sunder or disarm attempt, or would it have to be an attack?

Would you allow someone to ready a move and then choose a different destination (and possibly even movement type) based on what happens?

If the answer to those questions is yes, the answer to the spell one should also be yes. If its no, then all three should be no. If its yes and no, then you've got yourself some thinkin' to do.

 

[Artoomis]

...If your readied action doesn't disrupt the original caster's spell, may he choose to do something else based on your triggered action?

I think the rest was answered satisfactorily. As for this point, no. The action that triggers a readied action happens (or is prevented, maybe, like with a counterspell).

If you don't do this you end up with a time paradox. It could play out like this:

Player 1. I cast magic missile.
Player 2. Before your magic missile goes off, I cast a shield with my readied action.
Player 1. No, wait. Since his shield goes off first, I changed my mind and cast a fireball.
Player 2. Not so fast. Since he really cast a fireball and not a magic missile, I don't want to cast my shield with my readied action that goes off before his spell, but want to cast a fire resistance instead.
Player 1. No, wait...

 

[Keith]

In my view, you can either ready to cast a spell when someone else starts to cast, in which case your action occurs before theirs (you can’t identify their spell), or you can ready an action to occur once you see the results of a spell an opponent casts (using Spellcraft or plain observation). Either way, it is DM determination whether you have to ready a certain spell or just ready casting.

Reacting to a spell while it is being cast is counter-spelling, in my view; you can cast the same spell if you have it available, make your Spellcraft check, and readied counter-spelling. Again, depending on DM preference, you could use Dispel Magic, or might have to have identified it by name when you readied it.

While the idea of responding like lightning to the casting of Magic Missile with a Shield is cool, I think it is entirely outside the intent of the D&D magic rules. If this were possible, it would be front and center in magic combat rules. Or, the rules are cooler than I thought, which would be fine.

 

[Thornir Alekeg]

from the SRD

Readying to Counterspell: You may ready a counterspell against a spellcaster (often with the trigger “if she starts casting a spell” ). In this case, when the spellcaster starts a spell, you get a chance to identify it with a Spellcraft check (DC 15 + spell level). If you do, and if you can cast that same spell (are able to cast it and have it prepared, if you prepare spells), you can cast the spell as a counterspell and automatically ruin the other spellcaster’s spell. Counterspelling works even if one spell is divine and the other arcane.
A spellcaster can use dispel magic to counterspell another spellcaster, but it doesn’t always work.

I read this to mean you must declare that you are readying to counterspell. If the target begins casting, because you readied to counterspell, you get your Spellcraft check, and can then counterspell with the identical spell. The only flex I would allow in this would be to allow the counterspelling caster to use Dispel Magic if the identical spell is not available. You cannot put up a Shield or cast Dimension Door instead.

 

[Grayhawk]

Reacting to a spell while it is being cast is counter-spelling, in my view; you can cast the same spell if you have it available, make your Spellcraft check, and readied counter-spelling. Again, depending on DM preference, you could use Dispel Magic, or might have to have identified it by name when you readied it.

You have to use the ready action to counterspell, and you don't have to state up-front which spell you will counter with (that's what the spellcraft check is for).

The question is whether it's allowed to ready an action to either counterspell, disrupt or cast a personal spell, or if you need to choose one of these when readying.

While the idea of responding like lightning to the casting of Magic Missile with a Shield is cool, I think it is entirely outside the intent of the D&D magic rules. If this were possible, it would be front and center in magic combat rules. Or, the rules are cooler than I thought, which would be fine.

The Magic Missile/Shield combo was exactly what got me started thinking about this. While I agree that this propably wasn't the intent of the rules, does any of you see any gamebreaking issues that may come of allowing something like this?

 

[DarkMaster]

I think the rest was answered satisfactorily. As for this point, no. The action that triggers a readied action happens (or is prevented, maybe, like with a counterspell).

If you don't do this you end up with a time paradox. It could play out like this:

Player 1. I cast magic missile.
Player 2. Before your magic missile goes off, I cast a shield with my readied action.
Player 1. No, wait. Since his shield goes off first, I changed my mind and cast a fireball.
Player 2. Not so fast. Since he really cast a fireball and not a magic missile, I don't want to cast my shield with my readied action that goes off before his spell, but want to cast a fire resistance instead.
Player 1. No, wait...

In that case since Player 2 interrupt in the middle of the magic missile casting(since he rolled the spellcraft to recognize the spell being cast) the situation described cannot happen because the action by player 1 is already started but not completed. Situation would be different if the trigger of the action was based on the movement of the caster.

Player 2 as soon as this guy get in the 30' range I cast shield
Player 1 I move to be within 20' from my target and shoot my MM.
Player 2 I cast shield
Player 1 spellcraft roll, success, Oups he is casting shield, switching to fireball.
if the roll was a failure then he would have no clue what spell the caster made and he would have cast MM.

That is how I handle those situation, and I never have time paradox.

 

[jgsugden]

I think it is important to rememeber what these rules are supposed to represent. When you deady an action, you're getting set to do something so that as soon as you see a particular thing happen, you can finish your action - and do so before the other person finishes their action.

So, let us look at Able and Bob.

In game terms: Able is first in the initiative. He readies an action to cast a shield spell if Bob casts a spell at him. Bob then comes up in the initiative and declares that he wishes to cast a magic missile at Able. This triggers Able's readied action and Able casts his spell.

The game terms are meant to simulate the following events: Able notices Bob from a distance and realizes that Bob is going to try to cut him down with his favorite spell - magic missile, but knows that if he casts his shield spell too early, Bob will switch to his fireball spell. So, Able holds off on casting his shield spell until Bob begins casting his magic missile spell. The instant Bob begins to utter the words to his magic missile spell, Able rushes through his shield spell and puts it up.

Would it make sense under those circumstances for Bob to change his spell - in mid stream - to fireball? I can see allowing him to abandon the action in the middle of casting, but I can't see allowing him to switch actions.

The mechanic where we now place the PC that readied an action directly before the other being in initiative order is a game balance decision designed to prevent creatures from acting twice before another creature acts once. If we placed the readied character after the creature that triggered the ready action, the creature that triggered the ready action will get to use anything remaining in his round after the triggering event (often a move action) that turn and then will be able to take a full turn action against the creature that had readied against him in the prior round before that creature could act - providing a huge drawback for readying an action.

 

[Pielorinho]

I've not seen indications that a character is allowed to change their basic action based on a readied action that they triggered. If John casts magic missile at Bob, and Bob's readied shield goes off, then John can't choose to cast a different spell. He can choose not to cast MM, and I'd also let him choose a different target for MM, but he couldn't cast a different spell in addition to beginning a MM.

Similarly, if a fighter swings his sword at the wizard, and the wizard's readied dimension door goes off, then the fighter could choose to swing instead at the rogue next to him, or he could choose to sunder the rogue's short sword, but I wouldn't let him pull out a potion and drink it instead of attacking.

If someone readies an action against you and succeeds in using it, you've just lost a gamble that they set up: they gain the advantage. At that point, you suck it up and move on.

FWIW, I love readied actions and delayed actions, and encourage their use as much as I can while still keeping the combat fun; for this reason, I allow very broad statements of both triggers and actions readied.

Daniel

 

[Artoomis]

I've not seen indications that a character is allowed to change their basic action based on a readied action that they triggered. If John casts magic missile at Bob, and Bob's readied shield goes off, then John can't choose to cast a different spell. He can choose not to cast MM, and I'd also let him choose a different target for MM, but he couldn't cast a different spell in addition to beginning a MM.

I disagree. He's used up the MM, period. Once started, it cannot be aborted. Since the spell was identified with Spellcraft, clearly the spell is in progress.

More generally, you definitely should not ever let someone modify their action based upon what someone did with a readied action. To do so means:

1. The readied action is almost pointless - you are supposed to be seeing something the enemy is fully committing to do and reacting to it. It they can react to your readied action, then what's the point?

2. Possible time paradox problems.

...The (readied) action occurs just before the action that triggers it. If the triggered action is part of another character’s activities, you interrupt the other character. Assuming he is still capable of doing so, he continues his actions once you complete your readied action...

There you have it, right out of the rules. The spell is used up because "...he continues his action..."