How many poison counters does it take for a team to lose in Two-Headed Giant?

In a Two-Headed Giant format, each team of players shares a life total and collectively works towards victory or defeat. The unique aspect of poison counters in this format is that a team loses the game when their total number of poison counters reaches 10. Each player on the team can accumulate poison counters, and these counters are combined for the purpose of determining when a team is defeated by poison.

Thus, the pivotal number of poison counters required for a team to lose in Two-Headed Giant is 10. This aligns with the rules governing how poison counters work in multiplayer formats. The provided choice indicating 15 is not accurate since it does not reflect the established threshold for a team’s defeat due to poison.