Events, the Guild Member Shop, and the Guild Aid system are also great sources of Rare Catalysts like the Mysterious Flash.
Source #1: Unrecorded History 2-1 Grey Cliff Forest (Best Source)
Farming Stage 2-1 Grey Cliff Forest will allow you to get the most Mysterious Flash catalysts out of all the methods listed here. Not only are Mysterious Flashes featured as drops in this area, but they can also be purchased in the AP Exchange Shop. One Mysterious Flash costs 120 AP to buy, and you can only buy them up to 10 times per week. Although you can get them as drops as well. So buy only what you need, and make sure to equip pets that boost your AP acquisition rate whenever you run this Adventure stage.
Source #2: Events
Side Story Events have Exchange Shops that sell a variety of valuable resources — most notably Epic and Rare Catalysts. If that isn’t enough, we also have Login Events, Giveaway Events, and Minigame Events where we can earn Catalyst Chests just by participating. Make sure to keep track of and participate in as many Events as you can!
Source #3: Guild Member Shop
The Guild Member Shop is the most reliable source of Catalyst Chests in the game. You should look at purchasing both the Random Rare Catalyst Chests and the Random Catalyst Chests if you want to get Mysterious Flash. Whether or not you get that specific Catalyst depends on RNG when it comes to these random chests, but I would still recommend buying at least one of each of them every week regardless.
Source #4: Guild Aid
Another useful perk of being in a Guild is the ability to use the Guild Aid system, which allows you to request Runes, Catalysts, or Crafting Materials from your guildmates. You can only do this once every day, and you cannot change your selected material until after the day resets. Do not be a freeloader and give back as much as you take. Requesting Catalysts often while not donating any yourself can be grounds for being kicked out of a very strict Guild!
