I'm thinking more of a Merlin-like quick support, so more focused on bosses than NP looping with the help of a 50battery:

1 - A targetable skill that's a bit similar to Artoria's upgraded Mana Burst: It buffs an ally's quick card, then it changes all their cards (but not np) to quick for 3 turns. It's great synergy with Skadi's 100% quickCrit buff, but it's also a demerit because a buster card with no buffs still does more damage than a quick card with 50% quick buff. Maybe it could increase their star absorb and come with a star bomb as well?

2 - Team debuff clear skill. Similar to Jane's S3, activating it with more stars grants additional effects: debuff resistance, healing, np battery, invul.

3 - Similar to Oberon's 3rd skill: When maxed, it doubles an ally's NPdamageBuffs. It does not come with a sleep demerit, but it drains NP (maybe 50 from self and/or the target ally) and requires stars (maybe 50 again) to activate.

NP - Uh, idk... make them ST just to be unique lol.