For Professor Onyx’s last loyalty ability, “this process” is the following: First, the next opponent in turn order may choose a card in hand without revealing it, then each other opponent in turn order does the same. Then all the chosen cards are revealed and discarded at the same time and each opponent who didn’t discard a card (whether they chose not to or had an empty hand) loses 3 life. This all will happen seven times, for a maximum loss of 21 life per opponent.