ACHIEVEMENT - HOW TO UNLOCK
Archmage - Unlock 30 cards for one deck
Auramancer - Win a duel controlling at least five Auras
Avatar of Slaughter - Win a duel when an opponent controls no creatures
Beast Within - Win a duel controlling a creature with at least 10 power
Challenge Master - Solve ten challenges
Dragon Slayer - Defeat Nicol Bolas in the revenge campaign
Fearless Explorer - Defeat ten encounters
Flawless - Win a campaign duel with 20 or more life
Fury of the Horde - Win a duel controlling at least twenty creatures
Guildmage - Defeat the Sepulchral Strength deck in the revenge campaign
Insurrection - Win a duel online using an Expansion 1 deck
Jack of All Trades - Unlock a card for each of ten different decks
Last Mage Standing - Win a 3-player, 4-player, or Two-Headed Giant duel
Maelstrom Wanderer - Win a Planechase campaign duel
Magic: The Puzzling - Solve a challenge
Master of the Wild Hunt - Win a duel controlling at least ten creatures
Memory Adept - Enter the deck manager
Mythic - Cast a mythic rare card
Near-Death Experience - Win a duel with exactly 1 life
Otherworldly Journey - Win a duel online
Praetor Slayer - Solve the Say Your Praetors challenge in all five ways
Savor the Moment - Win a campaign duel with an opponent's library empty
Sky Summoner - Defeat Talrand in the campaign
Time of Heroes - Defeat an encounter
Two-Headed Giant - Win a Two-Headed Giant duel

The Praetor Slayer achievement requires the player to complete the challenge "Say Your Praetors" in five different ways -- each one requiring you to kill a different Praetor. However, thanks to this major glitch with the way the challenge works, you can easily unlock this achievement once you've found a method to kill any of the five. First, discover or look up any method of completing the challenge. Now, go back into the challenge, but this time buff up your Baneslayer Angel any way you like so that she can kill one of the other Praetors on the defense. After the Praetor has been killed, bring up the menu and select Restart Challenge to begin again. This time, pick another Praetor and kill it as before, then restart again. Repeat the above process until you've killed each color of Praetor once, then finish by restarting and completing the challenge successfully. When the win screen appears, you'll be informed that you've unlocked the achievement