Items are basically abilities that, you can only carry one off. and you need to use it before you can collect another. forcing though choices. You always lose it by the end of the boss, too. The list here are just examples and ideas.

• discard a die. lose 2 health. change any 1 die to a 6.
• use this to add +3 to a roll. if you still carry this until the end of the boss, gain +2 VP.
• use this item to add +1 to a roll. if you still carry this item until the end of the boss, gain +1 VP.
• destroy this item, lose 1 luck, change any 1 die to a 6.
• destroy this item, gain 1 health.
• destroy this item, add +2 to the rolled dice result.
• destroy this item, gain 1 extra die to roll for this challenge.
• destroy this item, negate 1 damage done for this challenge only.
• destroy this item, gain 2 boost but lose 1 health.
• destroy this item, gain 1 health and 1 reroll.
• while you carry this item, your maximum health is increased by 1.
• destroy this item, LOSE 1 health.
• destroy this item, gain 3 rerolls if you still have this item at the end of the boss, gain 2 VP.
• destroy this item, gain 1 boost.
• destroy this item, roll 1d6, if the result is 1, 2 or 3 gain 1 health, if the result is 4, 5 or 6, gain 2 health.
• destroy this item, you may reroll any number of dice once.
• if you still have this item at the end of the boss, gain 2 VP.
• if you still have this item at the end of the boss, lose 1 health. if you destroy this item, lose 2 health.
• destroy this item, lose 1 health then gain 2.
• destroy this item, gain 2 boost.
• destroy this item, gain 2 health.
• while this item is in your inventory, you must reroll your die if it's a 6.
• destroy this item, gain 2 health and 1 reroll.
• while this item is in your inventory, your maximum inventory space is increased by 2.
• while this item is in your inventory, your maximum inventory space is increased by 3.
• destroy this item, gain 3 health.
• destroy this item, choose any 1 item to replace it with.
• destroy this item, gain 2 boost, roll 1d6, if the result is 1 lose 1 health.
• if this is still in your inventory by the end of the boss, you lose 2 VP. you can discard this at any time and lose 1 health.
• destroy this item and gain 5 health.
• destroy this item and add 5 reroll
• destroy this item and add 5 boost
• destroy this item, and automatically complete one challenge
• destroy this item, gain 2 more items and destroy one.
• destroy this item to gain 3 reroll
• destroy this item, pass the current active 1 star challenge.
• while this item is in your inventory, you may discard 1 health and gain 1 reroll.

Passive effect triggers (environments) for bosses in the optional hard mode.

• All items costs 1 boost less?
• destroy an item card at any time to gain 1 boost?
• pay one reroll to gain 1 health.
• you may destroy one reroll to decrease or increase the value of any die by 1. this can only be done once per challenge.
• items cost 1 more boost to buy.
• you may change any die roll of 6 to a 1, 2 or 3.
• you may discard 2 reroll to change any single die to any value.
• 3-star challenges cost 1 less boost to add a die to your roll.
• the base roll of all 1 star challenges is now 2d6.
• if the active challenge is 2 stars, substract 1 from the fail value.
• if the total of your dice are 5 or less, you may reroll any of those dice at no cost.
• you may change one rolled die to match another rolled die once per challenge.
• you may discard 1 health to re-roll any number of dice once.

Companions passive effects

• your maximum health is 4.
• your maximum reroll is 4.
• lose 1 boost.
• gain 1 reroll.
• gain 4 reroll.
• gain 2 reroll and 2 health.
• lose 2 health.
• gain 2 health.
• gain 1 health.
• gain 1 item.
• gain 1 health. add 1 to your next roll.
• gain 2 items

Target effects

• 11 or less - lose 2 health.
• 12 or more - gain 1 reroll.
• 3 or less - lose all your rerolls.
• 15 or more - gain maximum amount of reroll possible.
• 10 or less - lose all but 1 health.
• 18 or more - gain maximum amount of boost possible.
• 10 exact - you succeed in the challenge.
• 13 or higher - you gain 1 reroll.
• 12 or less - lose 3 health
• 15 or more - you may add a 6 to your next die roll.
• 11 or less - nothing.
• 12 or more - gain 2 reroll.

Bonus effects

• roll 6 - gain X.
• roll 3, 4 - gain X.
• roll 1, 2, 5 - lose 1 X.
• roll straight - gain 1 item
• roll pair - gain 1 reroll
• if reroll > 3 - gain 2 health
• if reroll > 2 - gain 2 boost
• if health < 3 - gain 2 reroll
• if health < 3 - gain 3 health.
• if health > 3 - lose 1 health
• if boost < 2 - discard this challenge without taking any damage
• if boost = 0 - gain 1 item.
• roll 1, 2, 3 - automatically clear the challenge