MTG March of the Machine spoiler explains new Battle type

An early March of the Machine spoiler dropped today, showcasing the new Magic: The Gathering card type and mechanic called Battle. 

The release of March of the Machine (MOM) will introduce a new gameplay mechanic to the game of Magic: The Gathering. Scheduled to drop into local game stores through prerelease events on April 14, players will experience attacking their own permanent to transform it. The MTG mechanic and card type is called Battle—Siege, and it was revealed today on a MOM spoiler from PressStart.