Costumes

Costumes give good stats and are important for set bonuses. Use the same jewels in costumes as regular gear.

For PvP: Rockstar (box no.2) is recommended for newer players

For PvE: Go for PvE Draconic (box no.11) until you’re able to obtain a gilded set [any or a specific one?]

The target is to try to unlock costumes as much as possible for collection buffs. Unlocking them all can cost anywhere between 500,000 to 1,500,000 gems (for every collector buff on all 11 costume boxes). So the best idea to reduce that huge number of gems is to open the free costume boxes daily, and wait for 50% discounts or boost % up for S++. These can be quite useful to get collections done at a lower cost. [what is boost % up for S++? for guilded?]

Gilded Costumes
Chances vary depending on the materials used for fusion, starting at 0.01% for A/A fusion up to 10% (20% during events) using two S++ costumes as material. [how often are events?]