This level, the final full-size one of the episode, has one of the most extensive and interesting layouts in the game. You begin in a room overlooking a large lava-covered outdoor area. You'll see a meandering string of pillars leading out to a platform in the middle of the area.
Go out the wooden door to a large central outdoor area that you'll see is surrounded by the lava-covered area. There's another wooden door, a gallows, and a tall building that was to your right when you exited the starting room. Inside the second wooden door is a room like the starting room; off to the right is a doorway dropping off into the lava, beyond which is a door in the outer wall of the area. Go back outside and look behind the row of columns behind the gallows, where you'll find a switch. Turn around right away when you walk up to it: a compartment in the outer wall nearby opens, with enemies inside that would have attacked you from behind. Hit the switch: it raises a bridge to the door in the outer wall.
Extra stuff outside
Your objective is in there, but there's a few extra things you can do outside first. You'll see that three of the pillars out in the lava are lower than the others, keeping you from running across them to the weapon on the platform. Go back to the door to the starting room and hit the switch next to it to raise one pillar to the height of the others. Outside the starting room, step up to the section of wall nearby that's at an angle and a lift will lower. Ride it up and hit the switch in the room above to raise a second pillar. Go back inside the starting room and follow the walkway to your left leading up and around the tall building until you come to a dark-metal surface at the end. Activate this to open a door, and hit the switch in the room inside to raise the final pillar.
Now, run along the string of pillars to the Hellstaff on the platform. When you reach it, sections between the pillars will rise into place, forming a solid walkway. Instead of returning this way, look along the outer wall near the corner out beyond the platform for a narrow ledge just above the lava. There's a hidden doorway here to a secret area with an item. The teleporter leads to the gallows. (The single pillar next to the remaining gap in the completed walkway will lower when you run against it. This is a way out of the lava if you fall in.)
Opposite the central area from the walkway, along the outer wall on the south side there's an overlooking area where some enemies may be firing at you. Look to the right of this for a recessed area in the outer wall down at the lava. There's an item here; to exit, look for a nearby teleporter opposite the lava. To the left of the south overlook is a barred-off lava-filled channel leading away, where a Disciple of D'Sparil may be firing at you. (Odd place for a member of the clergy.) In the corner of the central area closest to this, a section juts out a bit. This is a lift: if you fall into the lava in this area, run against the jutting-out section and the lift will lower. Finally, you can probably clear out enemies through the windows of that overlooking area in the outer wall to the west, out past the far side of the tall building, as well as inside the one behind the gallows.
When you're done outside, go through the door in the outer wall past the walkway you raised. In here is a tall narrow hall with a narrow door to the right, a door up some stairs ahead, and a doorway to the left leading to a larger room with stained-glass windows. The narrow door goes to an elaborate room: the one that overlooks the area behind the gallows. In here is the Green Key out of reach on a pedestal. There's nothing to do in here for now, but you can clear out enemies. In the tall/narrow hall, go up the stairs to the room beyond, where you'll find the Yellow Door. Step up to it and then turn around, and you'll see a nook has opened with a teleporter inside. That's your next objective, but first, go through the narrow wooden door in this room, which leads to the overlooking platform in the stained-glass-windows room. Try and make a running jump to the nearest windows on the left and right. The one on the right is a hidden door that will open, with an item inside. The teleporter inside just goes out to the gallows. In both cases, jumping to the windows will cause various compartments to open, with Disciples of D'Sparil inside, so watch for them. But you'll get a lot of items in return.
Take the teleporter inside the Yellow-Door room: this goes to the overlooking area outside along the south outer wall. Take the stairway down to a tall green-paneled room with a water feature and various ledges and platforms. Above the ledge at the far end of the room is an even taller ledge with the Yellow Key. After clearing out the enemies, save your game: there's a hidden area in here you'll only have one chance to get into. First, note the two small ledges with the gold symbols below them. Step into the pool, and one of them will momentarily lower. When you step onto the lowered ledge, the other ledge will lower, revealing a small compartment and releasing an enemy. The second ledge will only lower once: when it does, run to it and ride it up, forcing your way past any enemies, and step into the compartment. In here is a Ring of Invincibility. To exit, step up to the inside of the wall/ledge and it will lower, plus the big ledge to your left will lower, with an Ethereal Crossbow.
To get the Yellow Key, ride the small ledge up, then jump onto the nearby big ledge on the long side of the room. The ledge with the Yellow Key will lower when you do. Ride the small ledge up again, get a good weapon ready, and jump do and collect the Yellow Key. The back wall will lower, with a big ambush inside, plus another area at the other end of the room will open, with enemies in there too. After fighting the enemies, go to that opened area at the other end of the room and look along the back wall for the misaligned section of texture. Activate this hidden door, where there's a small room to the right with a Map Scroll. Activate the back wall in here to open another door that leads to the barred-off lava channel, where there's a Mystic Urn and ammo. When you're done in here, return to the overlook outside. A walkway leading back to the central area will have risen into place.
Farther east and Green Key
Go to and open the Yellow Door. Inside here is a tall smallish room and the Blue Door. There's a nasty ambush coming, so have weapons ready. Step up to the Blue Door: this causes overlooks high on either side of the room to open, releasing a big crowd of Disciples of D'Sparil. It might be easier to exit back through the Yellow Door and fight them from outside. After getting them out of the way, go back to the Yellow-Door room if you haven't already, where two wood-paneled areas have opened, one with a teleporter, on either side of the Yellow Door. First, take the passages inside the wood-paneled areas to lifts that go up to the two overlooks where the ambush was. There are loads of items up here.
Next, go to the elaborate room where the Green Key is. The pedestal will have lowered, allowing you to collect it. Take a look on either side of the decorative panel at the low end of the room, at the small angled sections of wall with the gold symbols. These are doors that open whenever you step onto the lowered pedestal where the Green Key was. In here is a small room with an item. When you step onto the shelf where the item is, you'll get another minor ambush back in the main room from an area that opened to the side.
Return to and take the teleporter in the wood-paneled area in the Yellow-Door room. This goes to the area overlooking the west side of the lava-covered area. The nearby teleporter returns to the Yellow-Door room. Down the stairs, opposite the windows looking out, you'll find two Green Doors. First, look for ledges at either end of the area, with items out of reach. Near the Green Door on each side is a column with a switch. The switch momentarily lowers the ledge at the opposite end of the room, allowing you to reach the items. After collecting the items, enter either Green Door.
In here is a big U-shaped room, with a big red phoenix symbol on the floor, on which is a Phoenix Rod and lots of Flame Orbs. You'll take a bit of damage whenever you step onto this, so run fast if you collect the items. Stepping onto it also lowers those two tall pillars, with items on top. Find and hit the switch at the midpoint of the ledge along the inner part of the room: this lowers two lifts to the wide ledge along the outer wall of the room, where you'll find the Blue Key. When you pick it up, you'll get an ambush from either side of the room, but it's no problem; it's just Gargoyles, so this part of the level has been a bit of a break compared to all the nasty combat earlier.
Go back outside the Green Doors and up to where you teleported here, and take the teleporter back to the Yellow-Door room. Enter the Blue Door, which goes to a high room looking out over a second lava-covered outdoor area. Inside this room is a switch on a platform out of reach. It's possible to use your Phoenix Rod on the Iron Liches outside from up here, but the risk of backsplash damage from hitting the ledge in front of you makes it hazardous. There are Wings of Wrath available, if you want to avoid the lava. However you choose to do it, jump or fly down to the lava-covered area and to the walkway along the outer wall.
Near the ends of the walkway are switches: one momentarily lowers a big lift leading to the platform with the switch in the overlooking room (this is also the way out of the area if you need); the other lowers that outer barrier blocking access to the lift. Take the big lift up to the platform. When you step onto the platform, two areas outside along the walkway will open, releasing a couple Iron Liches, that you might want to take care of right away. Return to the platform if you need to, hit the switch, and a big center room along the walkway will open. After clearing out the released enemies (just Gargoyles this time, that are fun to take out with the Phoenix Rod while they're all still bunched together), look inside the room, where you'll find the level exit. Up next is the final level of the episode. Before leaving, remember all the Flame Orbs in the room with the Blue Key, if you used a lot in the last area.