At the beginning of each player's end step, that player draws a card. If the player is your opponent and has four or more cards in hand, Fevered Visions deals 2 damage to that player.
No player may take any action in between the two steps of Fevered Visions’s triggered ability, so if your opponent has four or more cards in hand after drawing a card, Fevered Visions will deal 2 damage to that player.