Is royal icing better at making summer musashis np refund consistent than Divine banquet? Those berserker waves always got me at that 94% with divine banquet.
Edit. I tried art of the poisonous snake and it works I just have to bring the mages association uniform for the last wave thanks for the advice.
Arts up is usually better than NP Gain for an Arts NP, but MUSAshi is not really meant to loop Zerks. Everyone has trouble on those. If you still want to try maybe swap to the Art of the Poisonous Snake. At MLB it’s 40% Arts for 3 turns. Also Paint on a Smiling Face has Arts, NP Gain, and NP Strength so it might help.
You could always just say “screw the CEs, I have a paracelsus” and just loop that way.
But BG, Smiling face, MLB k-scope, Sun princess, and (in theory) Cute Orangette, will work. But you may want to look at paracelsus just to be 100% sure to get refund. My mu-zerker is at np2 and is fine on zerks.
Summer Musashi is an uncommon case since she has a big NP Gain Up buff and no native Arts Up.
Assuming DCS, she’ll have +100% Arts Up/+110% NP Gain Up, so it’s true that she’ll get slightly more refund out of further boosting Arts, at least until those numbers are even.
For Servants who are packing a lot more total Arts Up compared to NP Gain Up, we usually get better refund results by increasing the latter unless overkill can make up the difference.
Fair enough. In my experience against Berserkers Arts is almost universally better because it’s more likely to give an additional hit of overkill by adding damage, but overstacking one effect does indeed have diminishing returns in every other metric so it makes sense it would also diminish refund to overstack. I’ve experimented with my Spishtar and noticed an MLB Poisonous Snake was better than Divine Banquet, but it’s also 40% Arts vs. 30% NP Gain so an unfair comparison.
I kind of missed the forest for the trees here.
You’re better off giving her a starting charge CE if you’re having refund problems but can still hit the damage you need to. You’re already 5-slotting, so you might as well make life easy. The only reason to use something like Royal Icing over starting charge in this scenario is that you need both more damage and more refund.
Do you have CEs with a starting charge? I think that would help your situation. I use Holy Night Supper typically but Demonic Sun Princess works too. Painting Summer might also.
I have an NP2 10/10/10 Lvl 100 Musashi Zerker (2K/2K fou’d and full Mana Loading) for reference. Not sure if you’re talk about a specific node, but I can 3-turn most 3/3/X berserker waves using that setup.
Also, I try to line up Arts chains with Castoria cards with Musashi’s NP. Some times it works out where I have a Castoria NP before Musashi to get the attack bonus. That helps on some of the beefier waves.
Edit: Gou beat me to it. 
Have you tried Magical Girl of Sapphire? That’s my go-to for fixing looping refund. 40% starting charge and big +NP Gain will usually work.
For Servants with a battery, Mark on a Smiling Face often works - that’s what I’m running with Sieg on the all-currency Zerker node (he full refunds 100% every time), and I also use it farming with Kiara. MGoS is generally “better” due to the starting charge.
Art of the Poisonous Snake can work if party cost is an issue, but it’s not as stable as the others.
Painting Summer is another great choice with 50% charge and +Arts, +NP Gain.