Hero Power: Gain 2 Armor.
Armor Up! is a Warrior class Hero Power card, that has Free rarity. Its effect is to gain 2 armor on your hero.
Armor works basically like Health, so you can see this as in a way healing 2 health with every use, and also as being able to take your health to above 30. This pairs well with Equipment cards as well, to provide some protection to your Hero while it attacks enemy Minions. Generally however, this should only be played if 2 more Armor/Health are required to survive next turn, or if there is nothing else in your hand that you can play, as summoning a Minion or a weapon is almost always better for gaining control of the game.
||Deal 1 damage to a minion for each Armor you have.