How do you determine the results of arson in an ancient city? Here is a table I created to figure this out in my World of Xoth campaign.
For fire damage the most important factor will be time. Given that the structure, and possibly the surrounding structures are flammable, once a fire starts it is only a matter of time before it burns everything around it. The following table uses an ascending order of magnitude (from sputtering out to reducing the city proper to ash) to try and model this.
1d12 City Fire Table (numbered result also reflects the number of hours the blaze burns):
Negative modifiers from -1 to -6 are applied to the initial fire roll to reflect any number of factors the Crypt Keeper deems appropriate for the current game situation, such as weather, available fuel, citizen response, etc. This modified result becomes your initial fire roll. This initial roll establishes the ferocity of the fire within the first hour. Any result of 6 and over requires an additional roll at the end of the first hour. If this second, unmodified roll is greater than the initial fire roll # than roll the 1d12 again. Either way, you finally end up on the final degree of damage caused by the fire at the conclusion of the number of hours the fire burned for.
Any result of 1 or less obviously means the fire didn't get very far and may certainly cause more problems for the PC than it was intended to solve. Then again, the same can be said for the other end of the table too.
01. Put out quickly by the city watch and concerned citizens. The evidence of arson is plain to see.
02. A small portion of the structure is damaged before the fire is quenched. Evidence of arson can be deduced by the wise and the experienced.
03. At least half of the structure is damaged, with some of this resulting in a total loss to items within the building. If the building was occupied there is an excellent chance there was loss of life. It will take some investigation to uncover arson as the reason for the blaze.
04. While the structure is still standing, there isn't a part of it which has not been ruined by fire or smoke damage. The locals may have their suspicions, but the damage makes it difficult to discern if the fire was deliberately set. Unless inhabitants of the structure were awake, or extremely lucky, many inside will have died in the blaze.
05. The structure is a complete loss, dangerous even to walk through after the fire is doused. Nothing of value would have survived and those who were unable to exit quickly will have perished in the flames. Only those who have had their suspicions aroused would be able to discern a deliberate act of arson is the cause.
06. The initial structure has become completely consumed and nearby structures have been damaged. At some point during the conflaguration the locals have given up on saving the original building and put all their efforts into stopping the fire from spreading further. Occupants of the neighboring buildings would have had time to escape harm.
07. Residents and shop owners near the blaze will begin to move valuables away, emptying out the silver cabinet and grabbing the livestock. The streets are clogged with frightened people and animals. Half the city will be aware of the fire at this point.
08. The initial fire has burned hot and bright enough to start multiple buildings on fire. Entire neighborhoods will be alarmed and these residents will rush to extinguish the fire. Who knows if their efforts will be successful?
09. The neighborhood watch appears in force. They will order citizens to risk their lives in putting out the fire if they half to, turning out common houses and gambling halls. People caught near the fire will be hard pressed to reach safety. Large numbers of people will start to move out of the neighborhood.
10. The city will muster all its resources in a final attempt to save the city. Property damage is now severe and countless lives are certainly lost. At this point the fire can be easily seen from a distance from the city.
11. Most people try to abandon the city. The fire has burned large enough that the inhabitants of the city have lost all ability to contain it. Whole neighborhoods are burning at the whim of the gods and the terrorized screams of man and beast ring out.
12. City engulfed. At least 60% of the urban landscape has been destroyed or effected by the raging inferno. The death toll is staggering. Many surviving citizens have been displaced by the fire.