Finding these counterspells with the London Mulligan

Figuring out the minimum number of [[Goblin Token]]s necessary to beat an opponent’s [[Stoneforge Mystic]] for [[Batterskull]] isn’t exactly uncommon in Legacy or the EPIC Storm in general. The chart above will help determine the amount of [[Goblin Token]]s required on a specific turn to overcome this scenario.

Ten [[Goblin Token]]s on the play are enough. On turn one, you make 10 [[Goblin Token]]s and your opponent plays a land. You attack for 10 (10 damage total) and your opponent plays land and plays [[Stoneforge Mystic]]. You then attack with 10 [[Goblin Token]]s again, and one gets blocked (19 damage total). Your opponent does nothing. When you attack a third time, your opponent activates [[Stoneforge Mystic]] and makes a Germ. The Germ blocks a token, letting eight tokens through but gaining four life for a total of four damage (23 damage total).

Note: With just eight [[Goblin Token]]s on the play, you deal eight damage, then seven, then two, leaving you with six [[Goblin Token]]s and an opponent at three life. Because the Germ has vigilance, it attacks on their fourth turn, putting them to six and effectively out of reach.

On the draw, you need more [[Goblin Token]]s. If you make 14 [[Goblin Token]]s on turn one, your opponent can play [[Stoneforge Mystic]] on their turn. You attack with 14 [[Goblin Token]]s and 13 get through (13 damage total). On your next turn, you attack with 13 [[Goblin Token]]s, your opponent forges [[Batterskull]] and blocks, gaining four life but letting 12 [[Goblin Token]]s through for eight damage (21 damage total).

Note: A dozen [[Goblin Token]]s would not have accomplished this. Also, notice that if your opponent has a turn one creature that can block twice (such as a [[Delver of Secrets]] that flips on turn one), they can survive even 14 turn one [[Goblin Token]]s!

If you are not making [[Goblin Token]]s until turn two, the situation is worse. Turn two on the play is the same as turn one on the draw, so once again you need 14 [[Goblin Token]]s. If you are on the draw, you need 18 [[Goblin Token]]s.

Suppose your opponent has just cast [[Stoneforge Mystic]] on their second turn. On your turn, you make 18 [[Goblin Token]]s When you attack on your third turn, they put [[Batterskull]] into play and block, letting 17 [[Goblin Token]]s through and gaining four life for 13 damage (13 damage total). Because the [[Germ Token]] has vigilance, it attacks, gaining them four life (9 damage total). You now attack with 17 [[Goblin Token]]s and both the [[Stoneforge Mystic]] and the Germ can block, so 15 [[Goblin Token]]s get through and deal 11 damage (20 damage total). Obviously, this plan is fragile as removing a single [[Goblin Token]] is enough give the opponent an extra turn.

After the second turn, it’s typically a good idea to avoid casting [[Empty the Warrens]]. Although, technically making 18 [[Goblin Token]]s on turn three on the play beats just [[Stoneforge Mystic]] into [[Batterskull]].

The math behind the engine