I think most of you are familiar with the story of Orion Pax, a peaceful, good-natured bot who was nearly destroyed by Megatron.
Invested with the Matrix of Leadership by the mysterious Alpha Trion, he arose as Optimus Prime, leader of the Autobot cause.
When Prime Fell in battle, the matrix eventually descended to Hot Rod.
It empowered him and made him into Rodimus Prime.
The Matrices will also allow interaction with a primemaster of your choice, empowering Optimus or Rodimus even further. This is a highly innovative concept, and great execution. I'm liking the new line a lot so far