In each event, there are three tiers of special event currency:
Tier 1 Currency is generated automatically at a regular interval (for example, an event might allow you to generate three pieces of tier 1 currency every five seconds). This tier of currency provides no boost or in-game effect. You can also use Gold to purchase tier 1 currency.
Tier 2 Currency is obtained by exchanging your tier 1 currency (for example, an event might have you exchanging thirty-five pieces of tier 1 currency for one piece of tier 2 currency). This tier of currency does impact your game. The effect varies, though it is generally related to boosting lobby production.
Tier 3 Currency is the most valuable currency in the event and can only be obtained by exchanging your tier 2 currency (for example, an event might have you exchanging eight pieces of tier 2 currency for one piece of tier 3 currency). In events that feature Loot Boxes, tier 3 currency is the currency that you'll need to obtain items from the Loot Box. This tier of currency also impacts your game. The effect varies, though it is generally related to boosting lobby production. It is also a stronger effect than the one that your tier 2 currency provides.
Collecting & Learning About Currency
On the left side of the Candidate screen in the Event, you'll see a circular icon that shows the tier 1 currency for the event (right above the crafting icon, which is indicated by a hammer and a wrench). Tap this to see an explanation of each tier of currency. This screen is also where you will collect your tier 1 currency (since it is generated automatically over time).
Crafting & Exchanging
On the crafting screen (accessed by tapping the icon showing a hammer and a wrench), you can exchange your currency. This screen will also allow you to use tier 1 currency to upgrade your equipped item (if the event features equippable items).
Exchanging tier 1 currency for tier 2 currency won't bring about any noticeable changes in the game. This is because the tier 1 currency does not actually provide any in-game boosts.
However, exchanging tier 2 currency for tier 3 currency can get tricky. Even though you are gaining pieces of tier 3 currency, don't forget that you are also losing tier 2 currency. When you make these exchanges, it can sometimes appear as though the tier 3 currency isn't working properly since you may see a drop in production. This is normal, since you lost the effects of the tier 2 currency. You will want to experiment with the way that you exchange currencies to find the optimal course of action for your play style.
There's some interaction between the three tiers of currency that can affect the results of exchanges. This interaction is something that we leave for players to discuss and figure out during each event. We encourage you to check out our forums to discuss the event with other players!