In modern speech, the word whom is almost unheard of. However, in RPG writing, especially fantasy, the use of the word is most appropriate provided it is used correctly.
Who is correct when used as the subject of a sentence, the subject being the thing doing the action of the sentence.
Groa stepped out of her tent and addressed the assembled men. "Who brought the news of Mennocin's shipment from town?"
Whom is correct when used as the object of the sentence, the object being the thing receiving the action of the sentence.
Groa stepped out of her tent and addressed the assembled men. "Whom do I have to thank for the news of Mennocin's shipment?"
In the first example, someone brought the news of the shipment. That someone was the subject; they did the action. Conversely, in the second example, Groa would like to thank someone for bringing the news. Groa is the subject (I in the example) and the person she has to thank is the object since that person is receiving the action.
It is important to make sure that your subject and your verb agree with one another. This does not mean they must be on speaking terms; instead, this means that they should both be singular or plural in nature. While this sounds simple, this type of error is actually very common. Keeping your writing in past tense does help to deal with this problem as many past tense verbs do not alter between singular and plural.
The troop of bandits are menacing in appearance.
Both Groa and Ruick is pleased with the troop's readiness.
Either Groa or Ruick were going to lead the troop in the attack.
The troop of bandits is menacing in appearance.
Both Groa and Ruick are pleased with the troop's readiness.
Either Groa or Ruick was going to lead the troop in the attack.
In the first example, the troop, not bandits, is the subject. Troop, while indicating multiple members, is a singular noun and requires a singular verb. This is the most common form of this error. The second example shows a noun linked by the word and. Though each individual noun is singular, the linked noun is plural and requires a plural verb. Finally, when nouns are linked by the word or, the verb should agree with the noun closest to the verb as shown in the third example.
In addition to your subjects and verbs agreeing with one another, your pronouns should also agree with your subjects.
The bandits each mounted their horses and prepared their weapons.
"If someone spots Ricktor Mennocin, they are to bring him to me. I want him alive."
Riders burst into the encampment. Clearing his throat he said, "The caravan has left the city."
The bandits mounted their horses and prepared their weapons.
"If someone spots Ricktor Mennocin, he or she is to bring him to me. I want him alive."
Riders burst into the encampment. The lead rider cleared his throat before he said, "The caravan has left the city."
Care must be taken when using words such as: everybody, anybody, anyone, each, neither, nobody, and someone. These words indicate the need for a singular pronoun: he, she, or it. The first example shows how to correct the problem by eliminating the word each; bandits requires a plural pronoun so use of the word their is acceptable. The second example shows the correct form using a singular pronoun. Though he or she is used, either pronoun could have been used independently, depending, of course, on the make up of the group. The third example shows a singular pronoun referring to the plural subject of the previous sentence. The corrected form redefines the subject of the second sentence making the singular pronoun correct.