Sweet Justice

Complete Special Missions and Quests to gain Bronze Hearts to get 6 unique Justice Set cards available for a limited time. There is a campaign mode with chapters, and a Marathon which lasts throughout the 21 days whereby the final top 500 get the event mythic card.

Getting Bronze Hearts gives you the same amount of Valentine Cups. The more Cups you got the higher you are in the Marathon. At the end of the Marathon the leaders are determined, and the Final Prize is given.

Hearts
The event features three types of Hearts : Bronze, Silver and Golden Hearts.

Bronze Hearts - obtained from opening duel chests, beating campaign chapters, purchase using gems, or quests which open in phase 2.

Silver Hearts - obtained from beating campaign chapters with 3 stars (only for the 1st time), or picking in a Bronze Valentine Coffer.

Golden Hearts - obtained from winning the event daily tournament (top 50 with most Valentine Cups each day), or picking in a Silver Valentine Coffer. In phase 3, they are removed and converted to Gears for the MA (see below).

Coffers
Bronze Valentine coffer - 3 pickings, 1 unique event card and Silver Hearts instead of cards are guaranteed. Unfortunately, you may be forced to choose between Silver Hearts and a unique event card.

Silver Valentine coffer - 5 pickings, 1 unique event card and Golden Hearts (Gears in phase 3) instead of cards are guaranteed. Likewise, you may be forced to choose between Golden Hearts and a unique event card.

Golden Valentine coffer - 10 pickings, many unique event cards and Artifact dups are guaranteed. Likewise, you may be forced to choose between Artifact dups and different unique event cards.

Event Cards
These cards can only be obtained by opening the appropriate coffers during the event.

Artifacts
Duplicates of the same artifact are combined to level it up, then inserted into any light card (without an ability). Assuming you have enough dupes, it is possible to upgrade an artifact during the next week (when it's no longer available), or even after the event ends, exactly like card seducing.

Justice Strike (10-20-35-50-65%).

Justice Revenge (3-6-10-15-20%).

Justice Retribution (5-10-15-20-30%).

Campaign
Like old events, campaign mode takes place in a familiar map, and you fight against 7 enemy cards like in duels, but battles require some Passion Power instead of energy, which fills slowly (+1 per 5 minutes) like normal energy, and is used to fight chapters to earn Bronze/Silver Hearts. There are 30 chapters in phase 1 :

Path
Starting from phase 2, you can earn Bronze Bells and Winter Stars by completing Path quests. Completed objectives will not reset at the end of the daily tournament. There is a X5 inflation for all XXX-Mas coffers !

Week 3 Magic Apparatus
On Stage 3 there's no coffer to spend Golden Hearts on. The Magic Apparatus (MA) took its place, and all the Golden Hearts are converted to Gears used to run the MA. You may get gears for performing different actions :

When you get enough Gears, you can run the MA to get one of the rewards, and also Points for the Marathon. You will not get Stars for the extra tries, though. After each run, the Apparatus heats up for a while. The hotter it becomes, the bigger the rewards and the chances to get the rarer cards. But the hotter the Apparatus, the faster it cools down. If you don't run the hot Apparatus on time, it would cool down to Level 1 :