using magic missle to disrupt a spell

[calighis]

Big debate about this one last night. Table split 3-2 with the DM in the minority.
Can a caster ready a spell like magic missile and discharge it to disrupt an enemy caster stating as a contingency "when he begins to cast his spell, I cast magic missile."
I voted in favor of it, but I would be interested in additional feedback.
Readying an Action

You can ready a standard action, a move action, or a free action. To do so, specify the action you will take and the conditions under which you will take it. Then, any time before your next action, you may take the readied action in response to that condition. The 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. Your initiative result changes. For the rest of the encounter, your initiative result is the count on which you took the readied action, and you act immediately ahead of the character whose action triggered your readied action.

 

[Rackhir]

Big debate about this one last night. Table split 3-2 with the DM in the minority.
Can a caster ready a spell like magic missile and discharge it to disrupt an enemy caster stating as a contingency "when he begins to cast his spell, I cast magic missile."
I voted in favor of it, but I would be interested in additional feedback.
Readying an Action

You can ready a standard action, a move action, or a free action. To do so, specify the action you will take and the conditions under which you will take it. Then, any time before your next action, you may take the readied action in response to that condition. The 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. Your initiative result changes. For the rest of the encounter, your initiative result is the count on which you took the readied action, and you act immediately ahead of the character whose action triggered your readied action.

You can ready to counterspell, so there's no reason why you can't ready to cast a MM. It's a standard action to cast a MM, so I can't see why it would be denied.

Can you tell us more as to why the DM disagreed? Is it some sort of a "balance" argument (IE. something along the lines of "It makes it too difficult for a BBEG to get off a spell.")

 

[Altamont Ravenard]

I as well see no reason why it wouldn't be possible, and Rackhir summed up the arguments.

At least now the DM has learned to give every BBEG spellcaster a Scarab of Protection

AR

 

[ClemLOR]

Well, why not?

You ready your action and define the trigger as: When target starts casting ..."
The target starts casting, triggering your action.
You cast your MM hitting the target 1-5 times each with 1d4+1 damage ...
The target needs to master a concentration check matching DC 10+damage dealt by your spell ... Bad luck means: He gets interrupted and looses the spell ...
I see no point arguing about it.

Greetings
ClemLOR

 

[freyar]

I agree with everyone else here; why should this be different than readying to shoot someone as they start casting? Isn't there even an example like this in the PHB?

 

[washout]

It's for sure possible, even better memorize a quickened magic missle as a 3rd level spell or even heighten it to up the spell level even further so that it can overcome a lesser globe. Then you can still fight and cast as normal and just have the quickened action ready for spellcasting.

 

[Jack Simth]

It's for sure possible, even better memorize a quickened magic missle as a 3rd level spell or even heighten it to up the spell level even further so that it can overcome a lesser globe. Then you can still fight and cast as normal and just have the quickened action ready for spellcasting.

That doesn't actually work, you realize - see, readying an action is, itself, a standard action - which means Quickening the spell into a swift action doesn't change anything.

Now, if you had a feat that made a spell an Immediate action, that'd be a different story.

 

[Delta]

Yes, by the rules it's allowed (even encouraged).

I can see how some DMs may not (a) realize this, (b) like this, (c) like being surprised by this for the first time.

 

[irdeggman]

I wonder if the OP (and/or DM) thinks that merely hitting a spellcaster with a magic missle while he is casting (i.e., disrupting the casting) will prevent the spell from going off.

If so that may be the reason why the DM is disallowing it.

The actual rule is if you take damage while casting a spell then you must make a concentration check to avoid having the spell disrupted.

Concentration: You must concentrate to cast a spell. If you can’t concentrate you can’t cast a spell. If you start casting a spell but something interferes with your concentration you must make a Concentration check or lose the spell. The check’s DC depends on what is threatening your concentration (see the Concentration skill). If you fail, the spell fizzles with no effect. If you prepare spells, it is lost from preparation. If you cast at will, it counts against your daily limit of spells even though you did not cast it successfully.

CONCENTRATION
To cast a spell, you must concentrate. If something interrupts your concentration while you’re casting, you must make a Concentration check or lose the spell. The more distracting the interruption and the higher the level of the spell you are trying to cast, the higher the DC is. If you fail the check, you lose the spell just as if you had cast it to no effect.

Injury: If while trying to cast a spell you take damage, you must make a Concentration check (DC 10 + points of damage taken + the level of the spell you’re casting). If you fail the check, you lose the spell without effect. The interrupting event strikes during spellcasting if it comes between when you start and when you complete a spell (for a spell with a casting time of 1 full round or more) or if it comes in response to your casting the spell (such as an attack of opportunity provoked by the spell or a contingent attack, such as a readied action).

If you are taking continuous damage half the damage is considered to take place while you are casting a spell. You must make a Concentration check (DC 10 + 1/2 the damage that the continuous source last dealt + the level of the spell you’re casting). If the last damage dealt was the last damage that the effect could deal then the damage is over, and it does not distract you.

Repeated damage does not count as continuous damage.

Note that each magic missle counts as a separate attack and damage - you do not add up the damage to make the concentration check harder.

 

[Runestar]

And you have just discovered the reason why counterspelling is such a worthless option in 3e...