Confused is an effect that randomizes the cost of cards that you draw to be anywhere from 0 to 3. X-cost cards are not affected by Confused.
Note that the cost of cards in your draw pile or discard pile is not changed until you actually draw the card.Cards keep their new cost until the deck is reshuffled, or under another effect that change card cost, like Mummified Hand
Whenever you play a Power, a random card in your hand costs 0 for the turn.Frequently twitches, especially when your pulse is high.
Cards that are retained with Well-Laid Plans also keep the same randomized cost between turns.
Cards that have their cost reduced by Corruption will keep the reduced cost of 0.
Cards that are shuffled from Chrysalis will not be kept 0; their costs are randomized to 0-3.