You must complete
Terror your opponent's Wall of Air. Cast the following, in this order: Etherium Sculptor, Master of Etherium, Onyx Goblet, Loxodon Warhammer, Howling Mine. Attack with everything. Use the Onyx Goblet on your opponent.
CHALLENGE 10The solution to this challenge has changed since the Expansion Pack 2 update.
Cast Jagged Lightning, targeting the Angel of Mercy and YOUR OWN Mudbutton Torchrunner. Once the Mudbutton Torchrunner hits the graveyard, you'll be prompted to use its ability. Use it to deal 3 damage to your opponent. Cast Vengeful Firebrand. Attack with everything.
This is the solution that used to work, just in case it changes again:
Cast the following, in this order: Obsidian Battle Axe, Vengeful Firebrand. Let the Obsidian Battle Axe attach to the Vengeful Firebrand. Use Vengeful Firebrand's ability to give it +1/+0. Attack with everything. Usually this alone wins, but if your opponent blocks optimally, it leaves them at one life. All you need to do is assign the Mudbutton Torchrunner's damage to them.
Play a Plains. Attack with Ambassador Laquatus, then immediately hit X to stop the countdown. Cast Condemn on Ambassador Laquatus. On your second main phase, cast Kiss of the Amesha on yourself. Cast Wrath of God, and end the turn. Your opponent will cast Nightmare, and end the turn. On your turn, play a Plains. Cast Ambassador Laquatus. Use Ambassador Laquatus' ability three times on your opponent, and end the turn.
Note that this achievement was bugged when the DLC was first released, but has been fixed. If you earned it while it was bugged, and it's not showing as earned on xbox.com, here's how you fix it: Recover your profile on the xbox, then go back to the game, and replay challenge 9. This'll pop the achievement again.