Transformers: Legends Pits Optimus Prime Vs. Megatron

DeNA has big plans for Transformers: Legends in the form of an exclusive episode that pits longtime rivals Optimus Prime and Megatron against each other. It's the first in a series of weekly episodes that will run through September. In addition, this is the first time Optimus Prime has appeared as an Ultra Rare (rarity five) card.

From DeNA:
In this episode, the conflict between the Autobots and Decepticons has come to a head and Megatron is leading an all out assault on Autobot City. It's up to you to take on the Autobots and help Megatron overwhelm their forces to finally face off with Optimus Prime. The One Shall Fall episode also features familiar faces with the support of all-star characters Ironhide, Bumblebee, Shockwave, Jazz and Starscream.
The company has yet to reveal many details about future episodes, though we know Dinobots will play a role at some point. On top of that, gamers can compete against each other in a new PvP episode.