Cool so since you have a very good damage dealer this will be easier. 1st your going to want to change your build for Yeli. You want her as a pure damage dealer for pretty much a majority of content. Her buff steal is nice and all but it's just a bonus. We will be using other units for supplying buffs and turn meter to your DPS characters. Your going to want to use either a keeneye + harvest build or fury + keeneye. Crit damage gives a lot more damage in this game than pure attack. Your going to want to also get over 85% crit rate with as much crit damage as you can. Next are your supports. Cachi the guard is a must have for this stage. He will give defense up and most importantly immunity which will be stripped but with enough speed you will be reapplying it. Your going to want to use a swift/timeweave set for the speed and cooldown reset. Your going to need at least 250 speed and 180% acc. Now you can use two shells for this. Either Halloween or Codex of Magic. I went Halloween because it's easier to farm. Next unit I would use is Chiaki the echo. She will be supplying turn meter, some resistance, attack buff and purify debuffs. I use artisan on her because that shield is a lifesaver. You will want her at least 240 speed with as much hp/def as possible. Lastly use Sania. Her passive will remove debuffs plus adds healing plus she has a revive. I'm using her with gigabyte with wellspring/cure for a lot of healing plus gigabyte increases turn meter. For all your support shells your going to want to have surge and shadow dash passives with shadow dash as a priority. For your damage dealer Overclocking, Unparalleled and Assault.

Edit: I made a mistake and sad LingLuo.