Select the "Hands of Flame" deck once you have unlocked the card "Dragon's Claw" and play the first opponent in Campaign mode, Chandra Nalaar. Once the game starts you will have seven cards in your hand. Restart the battle until "Dragon's Claw" is in your hand. Play it immediately and wait out Chandra Nalaar's attacks. Defeat her monsters with spells and however else you can defeat them without reducing her life points to 0. Eventually with her red deck and your red deck, you should get the "Life Preserver" achievement in a matter of a few rounds. Once you have enough monsters to total 20 or more damage to Chandra Nalaar's life points, attack. This implies that all of her monsters she summoned earlier have already been defeated. The Mage difficulty setting is recommended.