When we reach the Island of Forbidden Caves, Talissa reveals that the dragon pearl is hidden beyond a portal, which can only be activated with a memory card locked behind a gate. To open the door mechanism, we need to restore it using gears that are scattered around the island.

You will encounter many obstacles throughout the cave that block you from going further. Luckily, all of them can be removed. 
 
Disperse the dark clouds using fireflies, which you can find by hitting the glowing mushrooms. Hitting one mushroom requires 15 energy and 1 basket.
 
Bats have nested in some of the rooms. Chase them away with 1 torch!
 
Repair the bridges that connect the islets inside the cave. 
 
It turns out the gears are protected by puzzles. The first one requires us to match the symbols displayed on the monuments with the ones on the floor in front of them. Keep pressing the buttons using your energy until the symbols match.
 
To get the second gear, we have to rotate the tiles on the floor until they form one continuous pattern. Rotating a tile once requires 10 energy.
 
The third puzzle requires us to calm the whirlwind blocking the passage. Search the cave to find the runes of the appropriate elements and subdue the whirlwind! You can find a hint about the relationships between the elements in front of the whirlwind.

After retrieving the memory card and passing through the portal, we encounter a snake named Rudolf Gubbenbaum XVI, who guards a second memory card. He will loan it to us for 200 fluorite crystals, which can be collected in the cave.

Beyond the next portal, the Guardians of Knowledge block your way until you solve their riddles. We have to look for the tomes of wisdom in the adjacent rooms – these books will help you find the right answers.

The second and third guardians will let you try to guess the answers to their riddles before you find all the tomes of wisdom. But be careful! If you guess wrong, you’ll have to defeat a basalt warrior in battle.
The warriors are formidable opponents. Consider searching for the tomes of wisdom to find the right answer to the guardians’ riddles and avoid fighting.
 
Finally, you reach the dragon pearl, but it’s guarded by the Dark Kraken’s tentacles. Defeat them to claim the pearl, which opens a portal to the spirit world.
Now Samantha and Taine can head to the Island of the Dragon Den to speak with the Dragon of the Celestial Sphere.

Hint: you can find empty pedestals in one of the libraries. Perhaps something will happen once they’re no longer empty!