The rules behind the counters

A player who has taken 21 or more combat damage from the same commander over the course of a game loses.

Casting your commander from the command zone costs 2 more for each time you have already cast it from there this game.

A player with ten or more poison counters loses the game. A Two-Headed Giant team loses at fifteen.

The monarch draws an extra card at the beginning of their end step, and loses the crown to whoever deals combat damage to them.

Whoever has the initiative ventures into the Undercity when they take it and at each of their upkeeps, until combat damage takes it away.

Once it is day, it becomes night after a turn in which the active player cast no spells, and day again after a turn in which they cast two or more.

With ascend, a player who controls ten or more permanents gets the city's blessing and keeps it for the rest of the game.

Start your engines! gives you speed 1; it rises by one at most once per turn when an opponent loses life during your turn, up to 4.

Two teams of two share one life total of 30, take their turns together and lose as a team at 0 life or 15 poison.

Every player starts with 20 life. Commander starts at 40, Brawl at 25 with two players and 30 with more, and a Two-Headed Giant team shares 30.

In a first or single game the players pick the starting player by any fair method, such as a die roll. In a match, the loser of the previous game chooses.