I am wondering if anyone has made sense of Gygax's spell interruption rules in the DMG - perhaps [MENTION=3586]MerricB[/MENTION]?
There seem to be multiple rules, and I don't think they fit together especially clearly:
* Players of spell casters must declare their spells before initiative is rolled (p 65) - I infer from this that you are locked in once the dice are rolled, and that if you lose initiative and then are hit by an attacker who won initiative your spell will be interrupted.
* Page 67 states a rule that allows a chance to interrupt a caster who won initiative, namely, if the absolute value of (weapon speed factor - losing initiative die roll) is less than the spell's casting time in segments (if it equal to the casting time in segments, then the spell is cast and the to hit roll made simultaneously).
* Page 67 also states a rule that says if initiative is simultaneous, the weapon strikes on its unmodified speed factor. This seems bizarre - the prospects of interrupting are actually better if you lose initiative (and hence get to reduce your WSF by your initiative result) then if you tie on initiative (and hence have to use your unmodified WSF).
* Finally, p 65 states the following, rather obscure, rule:
Some comments on this rule: (1) It seems to contradict the rule on p 67, for determining the segment on which the potentially interrupting attack occurs; (2) It is not clear to me, in light of the example, when the opponent's losing roll would ever be the correct roll to use to determine the segment on which the attack takes place. Is it intended as an alternative rule to that on p 67 for attacks that have no WSF? If so, it seems that such attacks will very often be slower than those made with weapons - because under the p 65 rule the attack occurs on the segment equal to the higher die roll, whereas under the p 67 rule the attack occurs on the segment equal to the difference between the WSF and the lower die roll.
Any thoughts or clarifications would be appreciated!
There seem to be multiple rules, and I don't think they fit together especially clearly:
* Players of spell casters must declare their spells before initiative is rolled (p 65) - I infer from this that you are locked in once the dice are rolled, and that if you lose initiative and then are hit by an attacker who won initiative your spell will be interrupted.
* Page 67 states a rule that allows a chance to interrupt a caster who won initiative, namely, if the absolute value of (weapon speed factor - losing initiative die roll) is less than the spell's casting time in segments (if it equal to the casting time in segments, then the spell is cast and the to hit roll made simultaneously).
* Page 67 also states a rule that says if initiative is simultaneous, the weapon strikes on its unmodified speed factor. This seems bizarre - the prospects of interrupting are actually better if you lose initiative (and hence get to reduce your WSF by your initiative result) then if you tie on initiative (and hence have to use your unmodified WSF).
* Finally, p 65 states the following, rather obscure, rule:
"Attacks directed at spell casters will come on that segment of the round shown on the opponent's or on their own side's initiative die, whichever is applicable. (If the spell caster's side won the initiative with a roll of 5, the attack must come then, not on the opponent's losing roll of 4 or less.) Thus, all such attacks will occur on the 1st-6th segments of the round."
Some comments on this rule: (1) It seems to contradict the rule on p 67, for determining the segment on which the potentially interrupting attack occurs; (2) It is not clear to me, in light of the example, when the opponent's losing roll would ever be the correct roll to use to determine the segment on which the attack takes place. Is it intended as an alternative rule to that on p 67 for attacks that have no WSF? If so, it seems that such attacks will very often be slower than those made with weapons - because under the p 65 rule the attack occurs on the segment equal to the higher die roll, whereas under the p 67 rule the attack occurs on the segment equal to the difference between the WSF and the lower die roll.
Any thoughts or clarifications would be appreciated!
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