When a character invokes a boon, must he use a minor action to sustain the newly invoked boon in the same turn for it to persist after his turn ends? For example, a cleric invokes Resistance on himself. Before his turn ends, does he need to sustain the Resistance boon?
The second example under “Sustain a Boon” in the Combat section suggests that a character must sustain on the same turn. Doctor Van Strankenkloff already has the Darkness boon. When he invokes the Shapeshift boon, he can only choose to sustain one boon at a time; he chooses to sustain Shapeshift, and Darkness ends at the end of his turn.
If a character must indeed sustain a boon on the same turn as it is invoked, how does one sustain the Summon Creature boon? Summon Creature has an invocation time of 1 focus action. When a character uses a focus action, he forfeits his major, move, and minor actions for the round. Therefore, the summoner does not have a minor action with which to sustain Summon Creature, and the boon ends at the end of his turn.