I did some calcs for W1-3 min-roll damage a while back:
(Edit: Sorry after double checking turned out I made small mistakes with Musashi’s W1 dmg. Also changed the MC buff for Ishtar to 2004 since in most setup she’d be using the NP gain buff as well)
- NP1 Space Ishtar: 53.8k/62.8k/102.9k with 1.0x class advantage and 50% NP buff from 2004 MC
- NP1 Summer Musashi: 97.0k/71.8k/107.6k with 1.5x class advantage and 50% NP buff from 2004 MC
(Edit3: made an error and included the 30% arts buff for Musashi’s W1 damage even though it’s supposed to affect only face cards, all Musashi W1 damage should be a bit lower)
Both assumed to have max skill levels, lv 90 with 1k fou, no attribute disadvantage, no CE equipped. Two max skill leveled Castoria assumed. Space Ishtar’s damage doesn’t take into account the RNG arts dmg buff, and Summer Musashi’s W1 damage takes into account using her double hit count skill (NP gain + 1 turn arts buff) as well as the dmg up + def down skill.
(Edit 2: If you use Musashi’s dmg up + def down skill in W3, she’d do 68.0k/59.1k/126.6k but that 3T dmg up would only be used for a turn)
Musashi would take 10% dmg penalty against earth types (a lot of W2 midbosses fall under this category, which made them a pain to deal with for Dantes), Space Ishtar is star type so she won’t suffer from this issue.
Between the two I’m leaning towards Castoria due to 50% battery, better refund, star type, and of course because she’s Rin.