Opening hand: Forest, Sunpetal Grove, Island, Birds of Paradise, Birds of Paradise, Birds of Paradise, Harrow.
Turn 1: Play Forest and Birds.
Turn 2: Draw Harrow. Play Sunpetal Grove, [[Harrow (sacrificing Forest) for two Forests. Play Birds and Birds.
Turn 3: Draw Time Warp. Play Island. Harrow (sacrificing Forest) for two Islands. Play Time Warp.
Turn 4: Draw Brilliant Ultimatum. Tap Sunpetal Grove and Birds for WW, three Islands for UUU, and two Birds for BB. Play Brilliant Ultimatum. The goldfish puts all five cards in one pile, so cast all of them. The cards, in order of resolution:
Dreamstone Hedron, Cloven Casting, Cloven Casting, Cloven Casting, Brilliant Ultimatum. The Ultimatum triggers each Cloven Casting. Tap the Hedron for 3 colorless mana and pay to copy Brilliant Ultimatum thrice.
Copy 1: Dreamstone Hedron, Dreamstone Hedron, Cloven Casting, Brilliant Ultimatum, Emrakul, the Aeons Torn. Tap the Hedrons for 6 and copy the resultant Ultimatum four times, one for each copy of Cloven Casting. You now have seven Brilliant Ultimatums remaining on the stack, two mana in your mana pool, and an extra turn.
Copy 2: Dreamstone Hedron, Emrakul's Hatcher, Emrakul's Hatcher, Emrakul's Hatcher, Brilliant Ultimatum. Tap the Hedron and copy the Ultimatum four times. You now have eleven Brilliant Ultimatums remaining on the stack and 32 cards in your library (the maximum deck size for this challenge is 61), so you can essentially cast all of them.
Cast all your Eldrazi first, four Coat of Arms to power them up, four copies of Quest for Pure Flame, and four copies of Bogardan Hellkite to power them up and deal 20 damage in the process. Add Madrush Cyclops to give them all haste. Then Nomads' Assembly for exponential Soldiers, Overwhelming Stampede for exponential power, and to top it off, World at War for four extra combat phases.
Activate the Quests, which multiplies all damage dealt this turn by 16. Attack with everything. Five times.
According to my calculations, you'll end up with 35 Eldrazi, 4 Dragons, 3 Birds, and a Cyclops, which means 33 creatures in play before Nomads' Assembly triggers. 33, then 66, then 132, then 264 Soldiers, for a total of 495 Soldiers.
Four Coat of Arms give each creature a total of +4/+4 for each other creature that shares a creature type with it.
The three Birds are 8/9, but they're tapped during the first combat phase. World at War untaps them, though.The Dragons are 17/17. There are 4 of them.The Eldrazi Spawn are 136/137. There are 24 of them.The Predators and Hatchers are 139/139. There are 6 of them.The Dread Drones are 140/137. There are 4 of them.The Soldiers are 1977/1977. There are 495 of them.The Cyclops is 3/4.Emrakul is 151/151.
At this point, the total power of creatures participating in the first combat phase is 983,495.
Then the first Overwhelming Stampede goes off, giving everything +1977. The second goes off for +3954, the third for +7908, and the fourth for +15806. For a total of +29655 to every creature.
There are 535 creatures participating in the first combat, so the Stampedes grant a total power bonus of 15,864,325.
Also, Bogardan Hellkite.
So at the end of the first combat phase, the total damage dealt is 16,847,840.
Damage is multiplied by 16 this turn, but there are five combat phases. Thus, the damage from a single combat is multiplied by a total factor of 80, bringing the total damage dealt by non-Bird combatants to 1,347,825,600.
The Birds are nontrivial because each of them has 29663 power, but they only participate in four of the five combats. 3 Birds * 29633 * 16 * 4 = 5689536 additional damage.
That brings the grand total to 1,353,515,136 damage.
EDIT: I forgot the extra turn from Emrakul! And all the copies of World at War that rebound. Attacking with 1,072,484 power of creatures five times yields a new grand total of 1,354,587,620 damage.
SECOND EDIT: Realized that I would lose the game during my extra turn due to having zero cards in my library. Fixed it by replacing one Kozilek's Predator with Platinum Angel. This reduces the total damage dealt by a small amount.
