Den of Fire
About Dens
All Dens are 1 floor dungeons that are obscured each time the Den is entered, with the Entrance and Exit (portal) tiles always visible. Most/all other map tiles are variable, and randomly change layout each time the Den is entered. Each den has one or two Boss fights on the way to the exit portal.
Chests in Dens can give you Blacksmithing Ore of different grades required for ehnancing gear beyond +4 and Elemental armor and weapon junk matching the Den. (Earth, fire, air, and water gear are steel grade.)
Info
The Den of Fire is the second den available to players. It appears after unlocking a new Right Hand of Reversal ability on the fourth level of the Second Abyss - Trade Waterways. After talking with Arna in the Royal Capital Adventurer's Guild it can be accessed from the Edge of Town.
The Fire Den provides some Low-Grade Ore (gray), mostly Mid-Grade Ore (red), and some High-Grade Ore (blue), and is a source of Fire Type armor and weapons (useful against Air Type enemies).
Boss Fights
The Fire Den has a mini boss fight just outside the portal room with a random set of fire-type creatures, and a final boss fight with a number of high-level Fire Hobgoblins sometimes accompanied by some other Fire Den monsters.
Exploration and Farming Strategy
Similar to the Earth Den, the Fire Den map reset prevents auto-moving to efficiently collect chests on the map. So the most efficient ore and junk farming strategy is usually to rush straight to the boss for guaranteed chest drops while picking up any nearby spawned chests along the way. Sprung traps are permanently revealed, however, so full exploration of traversed map tile variations once is of value to expose traps. Note that there are far fewer traps in this den than the Earth Den, and there are no traps that must be crossed to reach the boss. After a few rounds of exploration enough tiles should be explored and traps revealed to allow safe progress to the boss on further trips.
Note that the Fire den does not have entry and exit on opposite tile corners. Thus, most variations allow you to just travel over the four western tiles without ever visiting the other two. Note also that the walls of ajoining tiles are generally shown. As long as you see a three-square wide opening to either the west or the south from the exit tile, that way should be open to you. The only tileset found where you cannot enter from the west has a only 1-square wide passage to a deadend, and the only tileset found where you cannot enter from the south has no openings.
So, pick the route that appears wide open, and take as direct a path as you can to it. If you see neither west nor south open, leave the den and re-enter to draw a new tileset. Optional, reset until you see a chest spawned on the entrance or exit tile to increase the chest rate.
Den of Fire Maps
The Fire Den is another 2x3 map. The entry map with boss locations, tileset, and a several map variations are shown below. This is obviously an incomplete set of variations. Rather than tiles 'swapping' like Abyss map variations, there appears to be at least three variations for each of the three hidden tiles, suggesting at least 3^3=27 full map combinations.
That said, all 3x3=9 tile variations only need to be explored once for the traps to be permanently exposed for future runs. Really, only the 2x3=6 tiles closest to the entrance need to be checked. As stated above, the shape of the walls adjacent to the hidden tiles will be your primary indicator of the layout you're dealing with.
Den of Fire - Entry Map
Den of Fire - Some Variations
Den of Fire - Tileset
Credits
Den of Fire Map kindly provided by GrandAccelerator.