The Devil Treasure Room generated will be the same as the Treasure Room that would have been generated, minus the item and room textures.
Multiple-choice Treasure Rooms, such as those generated in alternative floors and ???, allow both items to be taken upon being converted to Devil Treasure Rooms. The blind item on alternate floors will still be blind, however.
This trinket also converts Treasure rooms on the current floor when picked up. However, this only affects Treasure Rooms that have not been visited yet.
The same goes vice-versa: dropping the trinket will convert Devil Treasure Rooms to normal ones unless they've been visited.
Devil's Crown does not affect the reversed Treasure Room in Downpour/Dross II.
Synergies
Golden Trinket / Mom's Box: Having either makes treasure rooms have a 25% chance of becoming a Number Magnet variant. Having both increases the chance to 33%.
Coupon: When used in a Devil Treasure Room, gives the item for free, acting like a regular Treasure Room but with devil items, only requiring the use of Coupon.
This doesnt affect the Angel Room chance, like how using Coupon in a regular Devil Room and grabbing the free item wouldn't.
Dream Catcher: Shows you the item that spawns without the trinket, allowing you to drop the trinket before entering if you think the treasure room item would be better than the devil deal.
Glowing Hourglass: Allows you to check the item that spawns with and without the trinket, letting you pick the better item.
Treasure Room is replaced with a 
Devil Treasure Room which contains items from the Devil Room item pool that can be bought for the usual number of Heart Containers normally requested (for the spawned item) in a 
Devil Room.
Angel Room chance like a normal Deal with the Devil would.
Red Key will be affected normally.
Magic Skin, 
VI - The Lovers?, 
XVII - The Stars?, etc.) will all be drawn from the Devil Room item pool.
Downpour/
Dross II.
Golden Trinket / 
Mom's Box: Having either makes treasure rooms have a 25% chance of becoming a 
Number Magnet variant. Having both increases the chance to 33%.
Coupon: When used in a 
Dream Catcher: Shows you the item that spawns without the trinket, allowing you to drop the trinket before entering if you think the treasure room item would be better than the devil deal.
Glowing Hourglass: Allows you to check the item that spawns with and without the trinket, letting you pick the better item.
More Options: All 
Broken Glasses, 
Golden Horse Shoe and 
XVII - The Stars cards buffed by 
Tarot Cloth.
Redemption: Devil Treasure Rooms will count as regular 
Devil Treasure Room (locked)
Devil Treasure Room (open)
