Raava is a powerful spirit from The Legend of Korra. She is a spirit of light.
Raava is a powerful spirit who wants to keep balance in the world. She knew that Vaatu was a big threat and sought to defeat him to save the world. Raava can be harsh on those for opposing her like Wan in the beginning but can also be gentle and peaceful while collaborating with her allies.
As a spirit of lightness, Raava holds a large amount of power than any other spirit and is capable of battling Vaatu, the spirit of darkness, for many centuries. In her battle against Vaatu, she was able to hold him down and attack him and hold her own against him. In doing so, she has a tendrils that can grip and hold onto her target making it hard for her target to escape.
Raava has the ability to merge herself with the avatar to enhance the individual's powers. As such during the merge, the avatar would have better prowess and control over the elements.