Chagren, the All-Seeing

When Chagren enters, each opponent reveals their
hand. You choose a card from among the cards. The player whose hand the card is in discards that card.

Whenever a player's hand is revealed to one or more players, put a +1/+1 counter on Chagren.

{4}{b}{b}{b}: Target opponent reveals their hand and outside the game. Choose a card from among them. Create a copy of it and cast the copy without
paying its mana cost.