Find the Storm Gem on the upper Tower of Knowledge staircase platform after the numbered gargoyle puzzle. It unlocks Endu’s storm attack and a separate special meter. To continue afterward, reach the switch below the platform; collecting the gem does not open every nearby locked door.
Reach the upper tower
The tower’s exterior entrance requires three outdoor gargoyle beacons lit with the Azure Torch. Once inside, ascend through the library and solve the balcony statue puzzle by lighting III and VII. Continue toward the upper rooms associated with Knowledge Keeper Wourha.
The large staircase and its upper platform are your pickup landmarks. Save during the ascent so an unsuccessful movement attempt does not erase the preceding tower route. The tower walkthrough connects the entrance, balcony and upper staircase in order.
Collect and identify the gem
Approach the pickup and check that the item is the Storm Gem. Endu has a dedicated socket for it, separate from the Wind Gem slots. Steam’s official achievement list links recovering it to Raging Tempest.
Do not infer the effect from the word “gem” alone. This is an offensive upgrade for the sword’s kit. If your immediate problem is a gap that needs one more dash, a Wind Gem is the relevant pickup instead.
Use Endu’s storm attack
After obtaining the upgrade, inspect Endu’s description and the special meter that appears alongside the movement indicators. Use the action assigned to that ability in your current controls and account for its charge requirement. The meter distinguishes this ability from an ordinary repeatable melee swing.
This guide does not assert a universal keyboard or controller input. Source descriptions use different labels for secondary attacks and movement actions. Check the current binding and the in-game ability description rather than applying a right-click instruction from a guide to every action in the sword’s kit.
The next route is below the platform
Locked doors near the pickup can make this area appear to end abruptly. Look down from the gem platform for a lower opening or ledge. Use Wind Dash to reach the lower route and activate the wall switch there.
The switch rotates the staircase. Follow its changed route to the elevator and the room where Budaen gives the Forbidden Archives Key. That key, not the gem itself, is the next requirement for the Archives route toward the Necronomicon.
Keep the upgrade systems separate
| System | Your reason to pursue it |
|---|---|
| Wind Gems | More consecutive movement charges |
| Endu weapon levels | Combat development and eligible evolution |
| Storm Gem | The sword’s storm ability |
| Forbidden Archives Key | Access to the next locked area |
A new special meter is not evidence that a movement charge is missing or that the key door should now be open. Identify the actual obstacle before repeating fights or searching the same platform again.
Sources and scope
Reviewed November 5, 2026 against the Storm Gem reference and Whisper of the House’s tower walkthrough. Achievement identity comes from Steam’s official data. This page does not claim a complete endgame sword-forging route.