monsters *slave = choose_random_monster_on_level(0, is_yred_slave, true,
                                                         true);

        // Choose a random slave in LOS.
        monsters *slave = choose_random_nearby_monster(0, is_yred_slave);
        if (!slave)
        {
            // Try again, without the LOS restriction.
            slave = choose_random_nearby_monster(0, is_yred_slave, false);
        }
        if (!slave)
        {
            // Try *again*, on the entire level.
            slave = choose_random_monster_on_level(0, is_yred_slave, false);
        }