When you enchant Niv-Mizzet, Parun with Curiosity, you create a devastating feedback loop where every single piece feeds the other endlessly. Because Niv-Mizzet deals 1 damage whenever you draw a card, connecting that damage directly to an opponent via Curiosity forces you to draw yet another card. That new draw immediately triggers Niv-Mizzet again, looping the process to deal as much damage as you need while drawing through your entire deck.