Every Little Bit Helps

Background
During your preparations for The Attack at Nightfall, you can add additional defenses against the undead monsters by telling Ser Perth about the oil barrels in the General Store.

Walkthrough
Go to the general store, select the oil barrels there, then talk to Ser Perth and he'll agree to set up a flame trap for the undead on the upper-level path.

Result
This will add fire to the village defenses.