Infinite Damage Turn One (Infinite Storm, Grapeshot): MtG Arena Historic

1/998 chance of a turn-one win! As of September 2022 this is the mathematically most-probable turn-one win.

We begin the game with any Leyline in hand (a series of Enchantments printed in M20 which start the game on the battlefield. We play a plains, and then the Alchemy card Fragment Reality which will exile the four-mana Leyline and put onto the battlefield from our library a creature with mana value less than four. The creature we fetch is Birgi, God of Storytelling, who generates a red mana every time we cast a spell. From there we cast one
Mox Amber followed by either another Mox, a Tormod’s Crypt, a Strike it Rich, or a Chalice of the Void. If one of the last two cards in our hand is Grinning Ignus, we can use the extra mana generated by Birgi to return Ignus to our hand and cast it infinite times. Once we’ve cast nineteen spells, the Storm ability on Grapeshot makes it lethal!

Deck
4 Chalice of the Void (MRD) 150
4 Fragment Reality (Y22) 4
4 Mox Amber (DAR) 224
4 Tormod’s Crypt (M21) 241
4 Leyline of Abundance (M20) 179
4 Strike It Rich (MH2) 143
3 Leyline of Combustion (M20) 148
3 Leyline of Anticipation (M20) 64
4 Leyline of Sanctity (M20) 26
4 Birgi, God of Storytelling (KHM) 123
4 Grapeshot (STA) 39
4 Grinning Ignus (STX) 104
4 Emeria’s Call (ZNR) 12
10 Plains (M19) 261
(or red/white dual lands to play out turn 2/3 wins—MDFC lands are for Arena Bo1 Algorithm manipulation purposes)