Neither but the second is closest, the cost is relatively small because the only time readied a readied action is used/desirable (to the people I play with) is when there isn't something better to do with their action. I aplologize for not wording it clearly enough. Example: The enemy out of range you'd generally want to take the ready action and set your trigger for when they enter range. Therefore the cost was small (as your action was wasted anyway) and you gain an attack you wouldn't otherwise get.
The fact that you'd only use a readied action when there's nothing useful to do with your action is why I consider the cost "high"; it has to offer some kind of real advantage to be an option that you'd ever use.
If you can attack and aren't trying to interrupt a spell (since that is left solely to counterspell) why would you ever take the ready action to attack mid beams thereby spending your action and possible reaction to often get less out of it while letting the enemy get more?
Because you might want to ready an action for "if the other party attacks us".
I've been with this thread since the beginning and mage slayer discussions in the past (before the timing was clarified) so this isn't newly trod ground for me.
Could you point me to a single instance previously in the thread of anyone talking about the state of an "instantaneous" spell which has been readied, and thus which is subject to being prevented from going off by attacks? If you don't ready a spell, there's no way for an attack to break your concentration on an instantaneous spell, because there's no concentration involved in casting an instantaneous spell.
Furthermore you're going off the point I was attempting to make.
Yes, that is because I was curious about a thing which I had not yet seen any discussion of. I am not only here to discuss your specific points, but rather, to discuss the topic in general.
I will attempt to elaborate. Your statement was and those are the discreet steps I was referring to. However, If you feel the need, and once again I don't advise it as its not supported, to break down spells into the discreet parts of casting time, resolution phase, and the individual effects in the resolution then your reasoning for allowing a readied trigger to hit before mage slayer doesn't work. Mage slayer attacks triggers when an enemy casts a spell which, in broken down magic, would occur before the between beam readied trigger but would still hit after it.
That's a good point; it's clearly generally the intent that the mage slayer attack happens after the spell has been cast, and that this would include the initial spell effects (such as people making saves, targets being selected, and so on). However, I think you're mistaken about the necessity of distinguishing between casting and resolution, because the rules for readied actions clearly make that distinction.
JC didn't break up spells into a cast and resolution phase which is what was being discussed. The method of resolving attacks isn't new.
I never said JC did that. See readied actions, page 193. "When you ready a spell, you cast it as normal but hold its energy, which you release with your reaction when the trigger occurs." We have a distinction here where you have cast the spell, but are now "holding its energy", which means that you're done casting but are using concentration to keep the spell ready for a reaction.
The ready action is different from the cast a spell action and has special rules because of it.
And even has special rules for readying a spell, which
change the way the "cast a spell" action works when you use ready to cast a spell.
Dispel magic targets lingering effects of spells not casters actively concentrating on them. You don't dispel the caster concentrating on hex you dispel the creature/object the hex is on. Or you dispel the effect itself such as with illusions.
Well, that's the interesting question. You're allowed to target a "magical effect". Is a spell someone is concentrating on a "magical effect"? It seems to me that it might be considered one.