The difference between these cards and Game Changers is that Game Changers, while strong, are labeled Game Changers with Commander's social setting in mind
With Zendikar Rising , however, Wizards backpedaled on all of this and stated that they would no longer be making mechanically unique buy-a-box promos
Enduring Renewal (Ext) The backbone of the "Fruity Pebbles" deck, which combined Enduring Renewal with Shield Sphere and Goblin Bombardment to deal infinite damage
And now, as you can probably guess, Sigarda's Aid and Stoneforge Mystic are rejoined under the banner of either Cloud, Ex-SOLDIER, Lightning, Army of One, or Cloud, Midgar Mercenary
once they're face up, they stay face up in the command zone and have effects until a condition is met that causes you to abandon them