Blizzeta, also known as Twilit Ice Mass: Blizzeta, is the fifth boss in Twilight Princess found in the Snowpeak Ruins. Blizzeta is actually Yeta after she has been possessed by the fragment of the Mirror of Twilight. After Yeta has been possessed, the windows in the boss room shatter inviting in a flurry of snow, turning the room in to an ice rink.
The battle begins with Blizzeta as an ice statue in the center of the room. Just pull out the ball and chain and hit her repeatedly with it. Once you hit her, she will start moving around the room rapidly. Just continue to z-target her and hitting her with the ball and chain.
After hitting her a few times with the ball, she will start to shoot out some mini-freezards. They really are just a distraction. Just completely ignore them and keep hitting Blizzeta with the ball and chain. After each hit, Blizzeta will get smaller and begin moving quicker until you've hit her 8 times. At this point she will completely break from the ice and then lift into the air.
The next phase of the battle begins and Blizzeta will be enclosed with more ice, with spikes of ice around her. The ice spikes that are around her will attack you. You can see their reflection in the ice when they are about to attack. Quickly roll out of the way when they do fall on you. Once the ice drops, pull out the ball and chain and break as many of them as you can.
After ice spikes attack, Blizzeta will drop all the ice spikes in a circle and then Blizzeta will drop in the middle of it. Roll out of the way of the circle and then once Blizzeta has landed, use the ball and chain to hit her. Afterwards, she will float back in the air and regenerate the ice spikes. The attacks with the spikes will start over. Repeat this process over again. Three hits to Blizzeta with the ball and chain will defeat her. At the end of the battle, Yeta returns to normal and Link is rewarded with a Heart Container and the piece of the Mirror of Twilight.