In this section

Historical Rules · 15 February 2021

Rule 808.5

Official source text from the 15 February 2021 Rules release

Permalink

In the Team vs. Team variant, a team’s resources (cards in hand, mana, and so on) are not shared. Teammates may review each other’s hands and discuss strategies at any time. Teammates can’t manipulate each other’s cards or permanents.

Find this number in the current Rules