Time to power on through the Infinity Stones as we take a look at the Power Stone / Gem. We've been going over the stones as Marvel 101's are doing the same and we've covered the Mind, Reality and Time stones so far. The Power Stone grants the user access to all of the power and energy that ever has or will exist. Which sounds… powerful. With the stone, the bearer can call on unlimited stamina and strength. It also allows for the duplication of almost any superpower. When used in conjunction with the other stones, the Power Stone boosts the abilities of the other already immensely powerful gems. The stone was in the possession of the Elder called Champion for a long time, but has also been used by Stranger, Thanos, Namor, The Hood, Reed Richards, Drax the Destroyer, Nebula, Adam Warlock, Titania, She-Hulk and even the Red Hulk.
In the MCU, the Power Stone appeared in Marvel's Guardians of the Galaaxy. The stone was inside the orb that was kept on the planet of Morag until it was reclaimed by Peter Quill / Star-Lord. Quill didn't know what he was carrying until Gamora lead him to the Collector who explained that it was one of the Infinity Stones. When the Collector's slave, Carina, tried to grab the stone, the power was released destroying much of the Elder's collection. Nebula was able to retrieve the orb and give it to Ronan the Accuser who placed it in his hammer and planned to use it to destroy Xandar. Quill and the Guardians, with the help of the Nova Corp and the Ravagers, were able to stop Ronan. They turned the stone over to the Nova Corps for safe keeping, where it remains as of now.
Here is the latest Marvel 101 showing a brief comic history on the Power Stone.