Dark Gem of Power

Dark Gem of Power is a Magic Item that comes with the Adventure Pack Concurrent Skies along with Lightning Bolt Cynder and Bone Chompy Summoner.

Console version
When placed on the portal, enemies' attacks are weaker. It lasts for around 45 seconds per chapter. Like with every Magic item, the figure can be removed from the portal to save part of the duration for later.

3DS and Super DS version
The Dark Gem of Power has the same effect in the 3DS, New 3DS and Super DS versions. However, it needs to be added in the hub world before it can be used in levels.

Trivia

 * Dark Gem of Power and Light Gem of Power are the only elemental Magic Items besides traps and vehicles.