Let’s take a close look at the sentence you presented:
“And if anyone did say anything, they would come in for years of torment too!”
We can see that a comma is at work in that sentence to set off the introductory element “and if anyone did say anything” from the main clause “they would come in for years of torment too.” That comma is needed there for clarity’s sake; it’s meant to make readers pause a little bit after reading the introductory statement so they can clearly comprehend it as a distinct and separate idea from the idea of the main clause. In the absence of that comma, there’s a clear and present danger of readers getting confused or becoming hesitant on what the sentence is trying to say. We can readily see the problem by reading that sentence, whether silently or aloud, without the comma:
“And if anyone did say anything they would come in for years of torment too!”
For stylistic purposes (particularly in dialogue), some writers would omit that comma to evoke casualness and spontaneity, but they risk getting the statement misunderstood when they do so. My advice then is to eliminate that risk by always using the comma in such situations.
To emphasize the value of the comma, I would even go as far as saying that it’s also desirable to use a comma to set off the adverb “too” from the main clause, as follows:
“And if anyone did say anything, they would come in for years of torment, too!”
With those two commas at work in that sentence, the intended sense becomes much clearer. But then again, the decision to use that second comma is best left to the discretion of the writer, for this time the decision is more stylistic rather than grammatical.
At this point, I must hasten to add that this clarification about the uses of the comma is just the tip of the iceberg, so to speak. In English, there are actually as many as seven other grammatical situations that need a comma. They are in addition to its three generally known functions of indicating a slight pause in the spoken sentence, setting apart items in a list, and separating a nonrestrictive clause or phrase from a main clause.
We can get a better idea of these multifarious uses from this definition of the
comma by
Dictionary.com: “the sign (,), a mark of punctuation used for indicating a division in a sentence, as in setting off a word, phrase, or clause, especially when such a division is accompanied by a slight pause or is to be noted in order to give order to the sequential elements of the sentence. It is also used to separate items in a list, to mark off thousands in numerals, to separate types or levels of information in bibliographic and other data, and, in Europe, as a decimal point.”
As to the specifics of these uses, I suggest you check out the
“Rules for Comma Usage” in the Guide to Grammar and Writing by the Capital Community College Foundation. The site offers the most detailed and most instructive discussion of the subject I’ve seen anywhere on the web, and I’d say that it’s a must-read for everyone desirous of mastering comma usage.