Historical Rules · 1 October 2012
Rule 811.5
Official source text from the 1 October 2012 Rules release
In the Alternating Teams variant, a team's resources (cards in hand, mana, and so on) are not shared. Teammates can't review each other's hands unless they are sitting next to each other. Teammates may discuss strategies at any time. Teammates can't manipulate each other's cards or permanents.