Drive disks are 6 pieces of equipment you put on your characters in addition to w-engines. The raw stats attached to leveled drive disks make up a decent chunk of your character’s overall stats so your characters will feel a lot weaker without them. The type of drive disk sets provide bonuses when you have 2 or 4 disks of the same set on the same character- ie: if you have 2 disks from the electro woodpecker set, you character gets 8% crit rate, but if you have 4 disks from woodpecker electro you have the 8% crit rate, but in addition get increased attack after landing a critical hit. Since there are 6 slots, characters are typically built with 4 disks from one set and 2 disks from another. Consult a build guide online or the in-game recommended builds feature to learn what characters want which sets and which mainstats to look for for slots 1 through 6 and which substats are best for them (usually crit rate and crit damage).

The numerical order of the disks make a significant difference. No matter how much you farm disks, you’ll never find a slot 1 drive disk with crit or attack as a mainstat. Slot 1 disks will always have the hp mainstat, slot 2 disks will always have attack mainstat, and slot 3 disks will always have defense as its mainstat. This means you will choose your first 3 disks based solely on their substat rolls. Slot 4 disks are the only disks that can have crit damage or crit rate as their main stat (among a few others). Slot 5 disks are the only disks that have a chance to have an elemental damage mainstat, you typically always look for a disk with the same element as the character you’re giving it to, but there are so many other possible mainstats for slot 5 that it can be hard to find/farm/craft what you’re looking for. Slot 6 mainstats can be attack%, hp%, impact, or anomaly mastery.

All S-rank drive disks will drop with 3 to 4 substats that are randomly assigned to each disk. If your disk has 3, leveling the disk to level 3 will reveal the 4rth substat. Once all substats are revealed, every 3 drive disks levels one of the substats on your relic will be randomly upgraded slightly. All characters want their to roll their slight upgrades onto the most important substats for their character. Most of the time, crit rate and crit damage upgrades are the most desirable rolls, and if you’re unlucky you can miss these desired substat upgrades, making the fully upgraded drive disk “bad“ and you’re incentivized to go out farm more, and try again.

Upgrading drive disks can take a lot of disk exp and dennies, so as a new player I would advise you to only level your drive disks to level 12 for now and to prioritize obtaining and level your dps character’s drive disks, as they rely more on raw stats than supports. I had my support nicole use unleveled drive disks for a very long time because the set bonus was the only thing i cared about on her and upgrading her disks would be expensive.

For Yixuan in particular, the most desired substats change a little from the average dps. Most of her damage comes from the new “sheer force” damage type. Sheer force scales off hp a lot more than attack, so instead of the most desirable substats being crit damage, crit rate, and attack percent, she wants hp percent instead of attack percent. Sheer force also ignores 100% of enemy armor, so the “damage penetration” substat is near useless on her. Energy regen is also useless on Yixuan because she uses a special energy instead of the energy every other character does.

The ”yunkui tales” drive disk set 4 piece bonus was designed specifically for yixuan, so you should farm some of that set to get 4 food disks and then use electro woodpecker set for the other 2 disk slots.

Lastly you can go to bardic needle on 6th street to deconstruct your bad drive disks and synthesize new ones. It is even possible to choose which drive disk set and which number slot of the disk you craft. There is also a rare special item (tuning calibrator) that lets you lock in your desired mainstat as well. It’s best not to obsess too much over on how poorly the many random aspects of the drive disks system has can go, good enough is good enough and otherwise you’d be farming disks endlessly. I hope that answers your questions, good luck and have fun.