There is a new parameter called "break", optional for both the success and failure sections. It defaults to 1 (so you should set it explicitly to 0 for some challenges) and is the percent chance that items get lost or break during this challenge. It should be low, because it is tested for all items, so a 5% setting (the max I recommend) means the group loses 5% of its items, statistically speaking, not a 5% chance of losing one item.
