Platform: Xbox One
There seems to be few walkthroughs for this part of the game which is very much different from the original. So, to reach the Source Temple in Phantom Forest in the Enhanced Edition of Divinity Original Sin, you need to activate 4 switches. It doesn’t matter what order you do these in, but there’s an ideal order the game developers wanted you to (Air, Earth, Ice, Fire). Honestly, though, it’s faster to go Fire, Air, Earth, then Ice. That way you’d have faster access to the unlocked stone door after the Ice switch.
Air (x:230, y:210)
I teleported a Source Hunter in through the gates, then picked up the key sitting on the crates to the left. Alternately, if your telekinesis is high enough, just snag it through the iron gate. Because the oil is annoying, I threw crates on top of the traps. Open the gates to let your teammates in, as there’s a Demon that will pop up you need to kill before starting down the stairs. Hit the switch at the bottom of the steps to the left of the next gate. It will light up green for success.
Earth (x:252, y:264)
Open the door next to the Air switch (or alternately come in from the swamp side of the map, though watch your step). Disconnect a character from your party. The sentinel will see you and make the insta-kill lava on the ground. I used my rogue with Winged Feet. There’s a round pressure switch on the ground near the goblin totem. Plop a crate on there which will open the door to where the earth switch is. I didn’t see understand what the switch did initially, so I parked my rogue at the Earth switch door and used my other source hunter with high telekinesis to throw a crate from the doorway. Then when the door is opened, you can continue on with Winged Feet onto the to hit the Earth switch, or use the 2 teleport scrolls in the corner to hit it. This will open the nearby door which is a path to the ice switch as well as cause the sentinel in the prior room to crumble.
Ice (x:224, y:350)
From the Earth room, head through the newly opened stone door. Whether you entered from the stone door or the swamp side, don’t step on the dark tiles as they are all switches that will activate insta-kill lava. I’m not sure what the totem does because I killed it first with my archer. Then I used Winged Feet and pulled the lever on the wall behind the totem’s back which eliminated the lava and opened the iron door to the grassy area. Now, find the 3 statues (knight, worshipper, and fish), then “move” them onto their respective 3 green pedestals (there are carvings on top of them). Then, as Izma said to Kronk, “PULL THE LEVER!” A green mirror will appear. Go through it and hit the Ice switch.
Fire
In the Ice switch room, there are levers. You’re supposed to split your team up and keep someone at the levers to open and close the doors below. That will help you reach the fire switch. You can’t just teleport through these gates because there are steam clouds that block your caster’s vision. In the multi-gated corridor there is a sentinel, lava and a metal crate. Seems complicated and time consuming because it is. The simple way is to head west near the wooden bridge to where there is an iron gate. Then just teleport yourself in, hit the Fire switch, the door opens, and voila! Alternately, you could have entered the area from the backside (there are two chests down that path around the left side of the area that leads to the multi-gated corridor) or even use the green mirror portal right behind where you enter to get the Air switch.
Hopefully it becomes of use to someone. In retrospect, I don’t understand how I couldn’t just figure this out on my own. The Air and Earth ones were easy, but the Ice and Fire had me running all over the place and wasting loads of time.