There are 5 types of Collections. Defender, Exotic, Event, Legendary, and Resource. Out of these, Event Collections are the only ones that are time limited. Each Collection will require you to find multiple copies of 2-6 different items in order to get the specified Dragon, Costume, or Resource reward. Once you have found all of the items needed for the Collection, you can trade it in from the Collections menu to claim your reward.
The most common way to get items is to send Toothless out on Explorations to Locations where a Collection Item of an active Collection can be found. After the exploration, there is a chance you will receive one or more of that Collection Item. See Collection Mechanics for more information about how items are distributed.
Some items can not be found in explorations. Items with a Green border around them can be found in explorations. Items with a Purple border are sold on Trader Johann's Ship for , , or . Items with a Red border can be found by search with a Legendary Dragon. These items are unique to that Legendary Dragon's Collections, with the exception of Crimson Goregutter which lacks their own Legendary Collection, and instead will find items for other Legendary Dragon's Collections.
Each Green border, Toothless searchable, item in a Collection has several numbers assigned to it which determines how many items you need, and how difficult those items will be to find. These values include:
Item Count: How many copies of the item are needed in the Collection.
Max Items: The maximum number of items that can be found in a single search bag.
Time Cost: The amount of time Toothless needs to search to have a chance to find the item.
Chance to Get: the percent chance to get the item after the Time Cost is reached.
Search Times: The length of time needed to explore the search location.
When Toothless explores a location, the game tracks a running counter of the amount of time the exploration took. Each bag adds to this counter the number of minutes equal to the search time. After each bag is added, the game checks this counter to see if it equals or surpasses the Time Cost for one of the items that can be found in that search location. If it has, the game uses the item's Chance to Get value to decide whether or not to award an item to the player. If the game decides to award an item, it divides the search time counter by the Time Cost, rounds down, and awards that amount of items to the player. If the amount of items is greater than the item's Max Items value, then the number of items will be capped at the Max Items value. The game then resets the search time counter to 0 minutes and repeats onto the next bag.
For example, let's say an item has a Time Cost of 2 hours, a Max Items of 3, a Chance to Get of 90%, and 1, 2 and 4 hour searches. Suppose a player uses 3 bags on the 1 hour search. On the first bag, 1 hour is added to the game's counter. Since this is less than the 2 hour Time Cost, no items will be found in this bag.
On the second bag, 1 hour is added to the counter brining it to a total of 2. This equals the Time Cost, so the game checks the Chance to Get value to decide if the player gets the item. The player has a 90% chance to get the item in this bag. Since the counter is equal to the Time Cost, the player will only get 1 copy of the item. If the player is unlucky, and does not get the item in the second bag, the game moves onto the third bag. An hour is added to the counter, bringing it to 3 hours. Since this exceeds the Time Cost, the game checks the Chance to Get value again. If the player is to be awarded an item, the game will only give one item. (3 hour counter time / 2 hour Time Cost) = 1.5 which gets rounded down to 1.
If the player used a 2 hour search, the first bag would cause the counter to meet the Time Cost, and so each bag would have the chance to get an item. If the first bag did not contain the item, but the game decides to award items in the second bag, it will contain 2 items since the Time Cost was met twice.
If the player used a 4 hour search, each bag will meet the Time Cost value twice, and will always award at least two items. If the first bag does not contain the item, but the game decides to award items in the third bag, it will only contain 3 items since the item's Max Items Value is 3.