First step is to get into the volcano. Head N up the steps and collect the lodestone. Next walk down either set of steps and drop a rope for Jen. Both proceed around above the door and drop another rope. At the bottom, collect a torch and ignite the two oil pots on either side of the door. The door will open, proceed inside, watch the cutscene and collect the Djinn form. Light some more pots and head through the door at the back. Follow the corridor to the rift gate. One of the chests at the back here contains a lodestone. Head on to the chalice of Sut and continue to the SW, opening the double doors that block the way. Head through the rocky passage to the N to the water puzzle.
Shift form and dive in. Swim along W and up out of the water. Turn the wheel and dive back in. Head S, then swim up in front of the locked gate, climb out to turn another wheel. Head back down and through the previously locked gate. Open the door to let Scree in. At the bottom of the pool in this room is a lodestone. Turn the wheel, and walk back into the first room. Dive in here and swim along to the SW area, just in front of the locked gate. Turn the wheel and this will open the final gate. Jump Scree into the final pool and have him climb up the wall to reach the final gate. Climb out and possess the statue to pull the lever making the first part of the bridge. Return Jen to the first pool, and use the summoning stone by the last pool to retrieve Scree. Head back along the rocky passage and then towards the E by a summoning stone. There is yet another lodestone in a breakable rock here.
Pick up a torch, then have Scree climb up to the ledge on the E wall and drop a rope for Jen. There is a lodestone at the top here too. Light the pots and enter. There is a tarot card lying on the ground in the large area, and also a lodestone in a breakable egg. Head S and down the ramp. One of the chests at the bottom contains another lodestone. The glowing door here is a wraith door; to get through it, change to wraith form and watch for the gap. When you get the sense of the timing, hold down O a little before the gap appears. When it does, run through it. There is a wheel on the other side of the door you can use to turn it off and let Scree through. There are a number of doors like this, they all work the same (all with a wheel on the other side too). Continue on to the next statue, collecting two more lodestones along the way. When the bridge is complete, head back the way you came (rope and all) to cross the completed bridge.
Continue along down the steps to exit at the SW and head toward the royal chambers. There is another Wraith door here. Enter it and turn it off to let Scree in. Head along to the centre circle and have lots of fun killing easy meanies. Get chucked into the pit. Oh dear, time to rescue Jen again. In the next area, collect the five lodestones (one in the centre and one at each corner). Possess the statue and open the mouth to open the door.
Next place the pedestal from the centre of the room on the N floor switch. Climb up the N wall and collect the torch and lodestone. Move the pedestal the S side and repeat. This time one of the chests contains a lodestone. There is a small door at the SE end, open this by lighting the pots and go through to turn the wheel and fill the pots in the larger door. Climb back down and light these to finally open the large door.
Follow the long corridor to the oil basin room. There are two lodestones on the floor here. Next climb up the SW wall and onto the walkway. Continue towards the statue at the end, zigzagging across the walkways. One of the walkways contains another lodestone. When you get to the statue, possess it and close the mouth. Proceed down the hole behind the statue into the now empty oil basin and through the hole at the back into the pipe room.
In the pipe room, climb up the S wall between the two columns. The top of the W column has a gem on it. Continue W over the statue head then climb down and cross the pipe. There is a lodestone on the pipe. Continue over more pipe and climb up the NE wall towards the E. Follow the pipes along the E wall to a wheel. Turn that to open the hatch that you passed. If you climb down by the wheel there is a tarot card. Run back and climb down the hatch. Continue through the shiny pipes and climb down into the water. Push out the grate to the N and climb down into the temple. Head up the steps for a cutscene.
Head S out of the temple and through the rocky passage. Near a column in the open, rocky area is a breakable egg containing a lodestone. Head S out of this area and then W through the lava temple from the central shaft. After a cutscene, you have to fight Jen, using the Egyptian style statue in the room. There are 5 lodestones lying around so that you can possess it; you can collect these before or after the fight. To beat Jen, you need to keep hopping around the side of her: make sure that you only hop backwards as forwards is way too slow. Then it's easy.
Head back to the temple through some tougher guards and watch the cutscene. Head out of the newly opened S entrance. One of the chests in this area contains a lodestone. Behind the chalices are a lodestone and a gem, and at the back there are two more lodestones. Possess the statue at the end and close the mouth. Walk NW into the next area; straight in front is a breakable rock containing a lodestone. Follow the passage around the broken rocky area. Negotiate this, noting that along the way one of the breakable rocks contains a lodestone and there is yet another lying on the path.
Exiting this area to the lava falls, one of the breakable rocks contains, well, you know what. Yet another one lies on the path. Have Scree climb the S wall and walk around to the other side. Collect the lodestone, possess the statue and rock it down. Have Jen edge around the N side then climb across the newly created bridge. Head out through the double doors. Kill the guards and light the pot at the N to open the door. Proceed S following the passage until you arrive at another locked door. The pots to open this door are above it, so have Scree climb up the east and west walls in turn to do this. There is a lodestone lying around up here too. Proceed through the door and then through the double doors at the end into the sanctuary.
Here, you must complete a lengthy procedure to open the large door at the S end. First, head up the stairs on the SW side (climbing up both sides to kill the annoying fire spitting people if you like first). As you head up there is a lodestone at the landing half way up. In the flame igniter area, if you climb up the S wall immediately after entering there is another lodestone. Head to the edge of the platform and have Scree drop a rope for Jen to climb down. If you climb down with Scree just N of here there is a tarot card to collect. Walk Scree along the wall towards the igniter; and edge Jen around. There is a ledge to jump up for which Jen must be in ferai form. Climb up the wall to the W with Scree and drop a rope for Jen. Have them both turn the wheel to fill the oil pot, then climb down to light the pot. Reverse the whole procedure and leave the area.
Next head back down the stairs in the main room and up the SE stairs. There is another lodestone at the top here. Head out into the flame igniter area, on the E side is a lodestone and on the W side is a pedestal and another lodestone. Carry the pedestal and place it on the floor switch. Have Jen jump up the W side in ferai form and stand on the floor switch. Walk Scree through the door to the next area, collect the pedestal from the back (which is next to a lodestone) and then place it under the door to stop it from closing completely. It needs to go on the different coloured section of floor; you can do experiments with the door if you have trouble with the precise location. Climb Jen down and both walk through the door. Ignite the flame, and then head W into the central shaft. Have Scree drop a rope, and climb down it. Follow the passage NW down the steps to the closed door and the wheel. Turn the wheel to fill the pots with oil.
Now have Scree return to the main room, and light the previously empty pots by the sides of the door that Jen is standing behind. Head up stairs, collecting a lodestone along the way. Head back to the central shaft, where there is another lodestone. Have Scree drop a rope at the SW part of the ledge, and climb Jen down. There is a tarot card inside a breakable rock here. To get to the igniter, possess the statue in front of it. Rock it down and walk across to ignite the flame. Return to the main room to take care of the last door.
To do this, simply head straight across to the W. This door is already open. In the large circular room, head to the S where there is a dripping statue. There is a lodestone by this. To solve this puzzle, simply climb up the walls at each side of the statue, head around the ledge at the top and light the oil pots. This completed, the main gate opens.
Return to the gate, head S through it and down the stairs. Keep going down into the hall of gods. There are plenty of big statues, so, well, time for some vandalism. Once inside, head E to the summoning stone where there is a lodestone on the floor. Get Scree to drop a rope off the S side of this ledge, then climb down with Jen. Leave Jen for now and climb down the N side of the entrance platform with Scree. Climb SW along the rocks, one of the breakable rocks here contains another lodestone. Once on the large central platform then find the rope (with a lodestone next to it) and burn through it. Head to the E side of the central platform and drop a rope. Next With Jen, jump onto the prong that forms part of the statue. Walk around the statue to the E platform and continue to the S side of it. Drop down onto the rocks (either in ferai form or with careful positioning) walk over to the rope. Climb up it. Then have Scree walk down back over the rocks to the E platform, to burn through the rope. There is another lodestone on the E platform.
Return Scree to the central platform by means of the summoning stone, then with him continue on and climb down the S side, heading across the rocks to the W platform. Behind the row of statues is a row of chests, one of which contains a tarot card. On the N side of the platform is another lodestone. Anyway, burn through the rope here and switch to Jen. With Jen, walk to the N side of the central platform, and edge around the back of it. Jump up onto the ledge at the very back in ferai form and then up onto the platform. Pull Scree out of the hat to burn through the final rope. Send Jen back the way she came and then pull Scree out once more using the summoning stone on the central platform. Climb Scree up to the enormous statue; possess it then rock it down. Drop a rope for Jen and both proceed across. Kill the guard and open the door. Proceed through with some pretty dangerous falling exploding lava rocks. There is a reasonably tough fight ahead as you have limited room. Best strategy is to run through, or back, somewhere where the lava rocks aren't. Makes it much simpler. If you get stuck with lots of explosions going off, best to Wraith run through them. Once through, head to the S door (there is an energy fountain and a rift gate to the W if you want to top up), and open it by lighting the pots. Do the same for the next door, and onto the battle with Goliath.
This is pretty easy. What you have to do is put out the lights; there are three sorts. Little lights, which you just kick over the edge, medium chalices, which you can push and large chalices. The way to get the large chalices over is just to stand behind them until the Goliath hits them and does it for you. Simply run back and forth until you've got everything. Occasionally the statue will clap and a whole lot of light will zap you; to avoid this, duck (with X). When you've finished it off, follow the passage out. There are a whole load of breakable rocks along the way, one contains a tarot card.
At the end of this section, Scree will get his body back and you will return to the Nexus for the final sequence of battles. Firstly, you have to fight Lewis, in each of your forms. (You can actually change form sometimes if you hold the buttons down when the scene starts, but it's not really a problem to do the battle in the right form). Lewis' energy meter depletes in four quarters; one for each of your forms. In ferai form, Lewis will run off to the back when you've depleted about 12.5% of his energy and start hurling hard to see fireballs at you. To avoid this, just zigzag around. When you've finished him off, you go into the water to fight in Undine form. Smack him up, and occasionally he will disappear and start hurling impossible to see missiles at you. These are really tricky to avoid. Just boost swim, stick to the edges and zigzag and you should be fine. Don't go on the floor as the fish mouths have some kind of machine gun that is really damaging. After the Undine form is the Wraith form. After a while Lewis will start Wraith dodging around. Do the same, and block whenever he comes near you and you shouldn't get hurt.
Next the fight switches to Scree. This is the hard bit; you probably have a stack of gems by now that makes the Jen fight really easy even if you muck it up. There isn't any of that for Scree, so be careful. Instead of fighting, immediately run and pick up one of the two shields on the floor. Then after you've bashed up Belazhur, or after some time, he will disappear into a machine in the centre and fire an energy beam at you. Hold R1 to use the shield. This will reflect the energy beam and stop it hurting you -- don't let it hit you as it is very damaging. Proceed to one of the spots of light when the beam is wandering around (you get a little time between attacks, but remember you can always stop and reflect the beam half way to avoid getting hit). When in the right place, the spot will hit the machine and disable part of it. Belazhur will jump back down, fight again and after a while he will hop back in the machine. Repeat until it destroyed. This is made easier by just moving back to the right spot during the fighting. Occasionally Belazhur will also hop up and fire fireballs at you (as in the coliseum), these are easy to avoid, just keep moving in one direction.
The fight now switches back to Jen in Djinn form. This is pretty easy, just keep whacking Lewis with the single long stick. Occasionally he will set the floor on fire, just stand somewhere else (e.g. on the steps). Watch the final cutscene, and that's all folks.