The glory of Phyrexia is marching to your town! You may have mixed feelings about this, and that's understandable. But no matter where you stand on the "please compleat me" to "free will is kind of cool" spectrum, March of the Machine has plenty of awesome new cards featuring several awesome new mechanics, so let's take a look.

For a visual overview of all the mechanics, check out the video below:

Battles

Phyrexia had success invading Mirrodin, so they're trying it again. Everywhere. But, just like the Mirrans, the residents of all the planes being marched on aren't taking it lying down. There are battles to be fought, so many that we have a new card type to represent them: battles.

Invasion of Fiora
Marchesa, Resolute Monarch
Invasion of Fiora // Marchesa, Resolute Monarch
 

Each battle in March of the Machine is a transforming double-faced card. The front faces (the faces you cast) are the first permanents to feature beautiful landscape art—landscapes being attacked, but as you'll see, that's thematic. But first, let's get them onto the battlefield. Battles can be cast during your main phase if the stack is empty, just like creatures, sorceries, and other non-instant spells.

Each battle enters the battlefield with a number of defense counters on it equal to its defense, found in the lower right corner of the front face. This tells you how much damage it takes to defeat a battle. Much like planeswalkers, battles can be attacked and damaged. But unlike with planeswalkers, the general idea isn't to cast them, protect them, and hope they stick around. You're battling to take them out.

A battle's subtype provides rules for how it can be attacked. Since every battle in this set has the subtype Siege, they all play by the same rules. (Could future battles have different subtypes and have different combat rules? It would certainly seem some bright, forward-thinking people set the system up that way.) As a Siege battle enters the battlefield, its controller chooses an opponent to be its protector. Every player except a battle's protector may attack it. Only a battle's protector may block creatures attacking it. Don't confuse protector for controller. You're going to attack battles that you control, the first time you've been able to attack your own permanents. Fun!

Battles are susceptible to more than just combat damage, though. Some spells and abilities may specifically say that they cause damage to be dealt to battles. Also, any spell or ability that says "any target" can target a battle, so get ready to stoke the flames of war.

Stoke the Flames
Stoke the Flames

Any damage dealt to a battle causes that many defense counters to be removed from it. When the last defense counter is removed from a Siege battle, the battle is defeated and a triggered ability triggers. As this ability resolves, the battle's controller exiles it then casts the back face from exile without paying its mana cost—and there won't be a mana cost, so that part's easy. The back faces are a variety of things; most of them are permanents like Marchesa, Resolute Monarch (long may she reign), but there are some sorceries in the mix.

Marchesa, Resolute Monarch
Invasion of Fiora
Invasion of Fiora // Marchesa, Resolute Monarch
 

Transforming Double-Faced Cards

In addition to battles, there are other transforming double-faced cards in the set. As a quick refresher, here are some of the key things you should know. The front faces of transforming double-faced cards are marked with a triangle facing up on the top left. The back faces are marked with a triangle facing down on the top right.

Elesh Norn
The Argent Etchings
Elesh Norn // The Argent Etchings
Elesh Norn
The Argent Etchings
Planar Booster Fun