If you put all permanents you control into one pile, you’ll have a two-thirds chance of not having to sacrifice any permanents, but a one-third chance of having to sacrifice all of them.

To choose a pile at random, each pile must have an equal chance of being chosen. There are many ways to do this, including assigning each pile a number and rolling a die.

You may put Auras or Equipment into one pile and the creatures they were attached to into a different pile.