Other reliable sources of Cold Looks (or Rare Catalysts in general) include Side Story Events and your Guild, which allows you to request Catalysts and purchase Catalyst Chests for Guild currency.
Source #1: Unrecorded History Stage 1-3 Dead Shadow Lake (Best Source)
Stage 1-3 Dead Shadow Lake is the best place to farm for Cold Looks, since you can only receive one other Catalyst as a drop here. So it’s very likely you’ll be able to stack a lot of Cold Looks quite fast! You can also purchase Cold Looks in this map’s AP Exchange Shop. You can buy up to 10 of them per weekly reset for 120 AP each. Tip: Always bring along Pets that can boost your AP acquisition rate when farming Stage 1-3 to maximize your AP farming potential!
Source #2: Events
Events either give away resources and materials for free, or allow you to earn them through farming Event Currencies and buying them from the Exchange Shop. And there are always Catalysts available in Event Exchange Shops. So make sure you participate in every event to farm all the Catalysts you need. There are also Pets that can boost your acquisition rate for event currency, so make sure to bring them along while farming.
Source #3: Guild Member Shop
The Guild Member Shop is one of the best and most reliable sources of Catalyst Chests. You can buy up to 5 Rare Catalyst Chests and 3 Catalyst Chests here every week, and doing so isn’t particularly hard. All you have to do is Donate every single day and you’ll have enough currency to buy all of the available Catalyst Chests.
Source #4: Guild Aid
Another great feature of Guilds is the Guild Aid system, which can be used to request all sorts of materials from your guildmates. If you’re in dire need of Cold Looks (or other Rare Catalysts in general) then you can request up to two Rare Catalysts once per day. Just don’t forget to pay it forward and donate some of your own excess Catalysts! Your guildmates will feel more inclined to donate to you in the future if you’re not just leeching off of them.