Each turn, a player must choose one of the three houses indicated by their identity card, if able. Some card abilities may restrict a player’s house choice.
If a player has gained control of a card that does not belong to one of their three houses, that card’s house becomes an eligible choice for that player while the player retains control of the card.
If there is no legal choice of house, the player plays the turn with no active house.
If a player is faced with two (or more) “must choose” mandates, the player may choose either of those options.