I used this build to grind out the 1,000,000 damage achievement as well as some of the other achievements along the way.
The combo is similar to another I saw on here that used the starting power and influence boosts of the final battle of the Into Shadow campaign to set up the combo. It uses
Messenger Hawk to copy
Talir's Unwinding a bunch of times to reset your opponent's hand so you can deal a ton of damage the creatures they replay. Instead of
Martyr's Chains boosting a bunch of your creatures power like the other deck used, I used
Champion of Order and protected it with counter magic until it started doing its thing. Once you have a board full of 999/999 creatures you just replay
Talir's Unwinding over and over and rack up the damage.
The only necessary cards are
Champion of Order,
Messenger Hawk, and
Talir's Unwinding, and on color merchants since I only had singleton copies of Champion and Unwinding. I basically filled the rest out with draw spells, search effects, and counter spells, as well as slotting in any other cards to try to get different achievements along the way.
Because you end up with so many copies of
Champion of Order in your deck as the game(s) go I eventually was able to get the
Mating Call achievement with this too.
Happy achievement hunting!