I called this guide the immortal yi since... well u know the Ultimates of soraka, Shen and Zilean? And u know Yis Mediate and the effect of guardian angel? That's it.

This teamguide is only an idea. I neither tested it nor tried one of those builds.
But nevertheless, maybe it is a good team?

Well if someone is crazy enough to test it i would like to see his comment here. So now.. what is the idea behind all those builds?

First Soraka since it is the easiest: Heal heal heal. She has to make sure that nobody dies so that the enemies dont become fed. Her Ultimate can help even when she is not near the fighting. Soraka can buy wards too.

Shen is the tank. Warmogs for his passive and surviveability, Rylais for more Life and a stronger Ultimate. Sunfire Cape for more Life and Armor. Randuins same + slow and Force of Nature against Mages... Well, a tank.

Twisted Fate is the distant ad Carry and the jungler, his Ultimate alouds him to get down running enemies he is more squishy than the others.. but hey, he is the carry.

Then Zilean, 540 ap for heavy bombs but not too squishy.

And yi, high amount of life and and a proper amount of ap making him an endless fighter in combination with his meditate, soraka's heal and so on.. i said it at the start of this guide.
At lvl 18 he can get around 500 armor and 400 magic resist in his meditaion.

Yi, Zilean and Twsted Fate are extremely good and fast farmers so that Shen could have problems with farming. As such it is strongly reccommend that shen takes the sololane. Besides, his taunt won't let the enemies be too dangerous for his tower.

I just added the items in a custom order, u should start with Dorans Items.
Shield for Shen and, as u prefer, ring or blade for the others.
Second item: shoes.
After that u better choose urself which of the items u need next,
depending on the current situation.

Well yeh.
Try it if u like and tell me how it worked.