Entering the keep, Kain progressed through a number of Straw lined corridors until he found his way to a large pyramid-like structure. Solving a puzzle involving colored Floor buttons, Kain was eventually able to lower a staircase to allow him to recover the item card at the front of the structure and gain the Flame Sword. Progressing back through another set of corridors, Kain was able to test the usage of the sword by using it to ignite the straw and to directly burn several enemies before returning outside to the swamp.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
The external appearance of the Flame Sword Dungeon consisted of two buildings in the far north of the western Termogent Forest area, with the first being a hollow rectangular rampart protecting the entrance to a further rampart embedded in the northern cliff which led into the main keep area - with potential links between the two buildings appearing long collapsed and ruined. The design of the buildings was reminiscent of the other buildings in the western Termogent Forest, such as the Control Mind Dungeon and the Blood Gout Dungeon, consisting of a dark grey ramparted building complete with crenellation and a flat roof, evocative of a medieval castle-like structure. The outer building was heavily eroded, worn and ruined, with a gaping hole in the front wall and another hole was positioned at ground level where traces of a former doorway of sorts were visible; damage was also visible in several spots on the roof. The smaller upper tower had less obvious damage, although bearing a similarly damaged doorway to the outer building.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
The internal area of the keep shared many design features with the other keeps of the western Termogent Forest, with distinctive maroon colored brickwork, marbled red doorways and weapons hanging from the walls. The keep was divided into five map areas:
The first area contained a wide 'T'-shaped junction with the main entrance at the bottom and the center bearing a mural of the flame sword. Three doors were positioned at the top of the area with one of the left junction and two on the right - with the left door leading to a square room containing a save altar, the right door initially closed and the 'middle' door leading onto the next area.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
The next area contained a number of Straw-lined rooms. Initially Kain entered in the bottom-right of a square room with straw patches around each of the walls and an exit in the top-left corner. This lead to a corridor heading north, lined with straw and with a chained prisoner half way up. Through a doorway the corridor turned right and headed east, where another straw patch and a prisoner were positioned on the upper wall, before the corridor turned south and passed through the exit door leading to the next area.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
Only the first room of the next area was initially accessible - consisting of a square room with straw patches on the north and eastern wall and with a wooden beam crossing horizontally in the roof, supported by two wooden pillars at either side of the room. The entry door was in the top-right, with a locked door leading to the rest of the area in the bottom right, and an open door leading to the next area in the south of the room.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
The next area was the largest in the building and was arguably the 'main' area of the keep, consisting of a number of walkways and platform atop a large red-bricked 'pyramid'-style building with several tiers visible.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
The initial area consisted of a large rectangular walkway surrounded by a fenced off darkened 'roof' area. In the center was positioned a square 'gap' with the entry door at the bottom, and this was flanked by two large rectangular fenced off pits, seemingly leading down the sides of the building. At the top-middle of the roof walkway was positioned an alcove containing a wall button. Directly to the south at the bottom of the walkway area, two further alcoves were positioned which overlooked several tiers of the pyramid below and effectivey flanked the entry door. Each of the four corners of the rectangular walkways featured a floor button rune symbol illuminated by colored light, with the top two illuminated red (along with the wall switch) and the bottom two illuminated green - each of the sides of the rectangular area also bore a number of wandering enemies, with three sets of two Blue peasant swordsmen and a Leaper vampire patrolling the top alcove and sides of the walkways. Pressing the top wall switch opened up a pair of staircases leading from the bottom alcoves to the tier below and treading on each of the illuminated symbols opened up the stairs to the third tier side platforms.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
The second tier consisted of a long horizontal platform with a wooden beam overhead. At each end of the platform was an alcove extending downwards overlooking the third tier below, where a rune triangle and a blood vial were positioned on the western and eastern platforms respectively. In the middle of the platform, either side of the stairs were a set of three alcoves extending north, each containing a floor button runes which glowed red. If each of the glowing runes on the top tier had been pressed, Kain could progress down a set of staircases that appeared on the edges of the platform to retrieve the rune triangle and blood vial on the third tier side platform. Activating the second tier runes and returning to the top tier to deactivate the bottom left and right runes - leaving only the two green runes at the top tier glowing - would lower the final staircase leading from the middle of the second tier to a platform atop the side of the 'pyramid containing the Flame Sword. Once collected Kain could return through the entry door.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
Returning to the beamed square room in the previous area, Kain would now find the northern door locked and the eastern door opened, allowing him to progress further into this area. The next room was rectangular with five straw patches dotted around the walls and as Kain entered two Zombies would rise from the piles on the western wall - with Kain now able to use the Flame sword to ignite the straw and burn them to death. Progressing south through the door led to a square room with a protrusion of straw from the western wall into the center where a Leaper vampire awaited. Again progressing south through an open door, Kain could continue to a corridor which headed south and turned to the west after a short while - with both sides lined by straw which crossed the room just after the entrance, and a chained human positioned on the northern wall of the western corridor. Two zombies would rise either side of the door to attack as Kain entered and he had to be careful as igniting the straw could burn the prisoner and his chance of refilling his Blood vial. A door on the northern wall at the end of the western corridor led up a set of stairs onto the next map area.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
The final area began with a plain 'L' shaped corridor heading north then turning west, with a chained human on the northern wall. A door in the south at the end of the western corridor led onto a larger square room containing a chained human on the western wall and a Leaper vampire in the center, with four zombies rising in the corners as Kain entered. After defeating the enemies, Kain could activate a switch on the northern wall which would open the exit door in the south. This led back to the right door in the initial 'T' junction area.[Blood Omen][Blood Omen/6][Blood Omen strategy guide]
The western area of the Termogent Forest containing the Flame Sword keep, Control Mind Dungeon and Blood Gout Dungeon is labelled in files as "Map 0001 Sect 43" and shares the same "Map 0001" designation as the rest of the overland areas of the game, including the eastern Termogent Frost containing Vorador's Mansion which is labelled as "Map 0001 Sect 44". The internal areas of the keep all share the "Map 0030" designation, with "Sect 00" referring to the opening hallway and save altar, "Sect 02" referring to the Straw-lined hallways with Chained humans, "Sect 10" referring to the large open pyramid-style area where the Flame Sword is found, "Sect 11" referring to the second set of straw-lined rooms, and "Sect 01" referring to the final rooms containing Zombies. The Developers' level select uses the label "FLSD" for the keep under the "OL5" designation, grouping it with the other buildings in the Termogent Forest. The main "OL" doorway under "OL5" also leads to western forest area.[Blood Omen][4]
As with other weapons related dungeons, the floor mural of the Flame Sword seen on the entry to the keep does not match the image on the card that Kain collects, instead bearing the icon that Kain carries when it is equipped in the full inventory.[Blood Omen][Blood Omen/6]