Madness

Will not activate on cards that already cost 0, but will activate on non-0 cost cards that have been temporarily reduced to 0 for the current turn through other effects such as and .
 will override the fixed 0-cost when the affected card is drawn again.
Also will not activate on X-cost cards.
A possible reward from the the Winding Halls event, though it can also be acquired from the normal Colorless pool.
==Update History==
*Patch V1.1: The Dealer
**All-Out Attack, Madness, and Reboot cards no longer affect Card Rewards when used (rng issue).
*Weekly Patch 8: Ooh Shiny!
**Colorless cards can now be upgraded! This was also a good time to re-examine and balance several of the cards.
**Madness is nerfed (costs 1 now). Upgrade cost 1 -> 0.
*Weekly Patch 5: Happy Holidays!
**Bullet Time now affects all cards currently in hand, works with Madness, and no longer applies a Power to you.
*Day 1 Patch
**When you use Madness, the card affected flashes gold now.
**Fix for Bite cards not loading correctly (it gave you Madness cards) when resuming a run.
**If a card fails to be identified you now get a Madness instead of crashing.