Chaos Emeralds

The Chaos Emeralds are seven incredibly powerful gems. It's rumored that if one were to have all seven at once, they'd be able to control the entire world.

Usage
In the IALR series, Sonic the Hedgehog can summon theses at will to turn into Super Sonic. However, he only does this when things are urgent, as he feels overusing the ability will bring disaster.

Trivia

 * They're similar to the human SOULs in Undertale.