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 Relic or Streamline.
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.
Update History
- Patch V1.1: The Dealer
- Confusion and Corruption cards utilize improved hooks.
- Fixed Bag of Preparation not drawing cards affected by Confusion power.
- Weekly Patch 47: Metamorphosis
- Fix for a scenario which upgrading cards affected by Snecko Eye would sometimes give negative cost cards.
- Weekly Patch 45: Impatience
- Confusion power will now work on Curses and Status cards that have costs.
- Weekly Patch 42: Reboot
- Updating SFX for Confusion Power.
- Weekly Patch 11: A Library of Features
- Enchiridion now works with Snecko Eye properly.
- Weekly Patch 8: Ooh Shiny!
- Confusion power can now affect Colorless cards.
- Weekly Patch 2: Slimes!
- Eviscerate now correctly works with the Confusion debuff.