At least Siegfried helps a lot in farming for the poison needles.
I would wait unless you have 5k mana prisms on the spot tbh
but if I had to pick I would pick sumanai since - wait, you don't have the free Lily?
Stheno buffs herk and kintoki
Sumanai just sits in my party trying to be a hero
There are way better buffers than Stheno given you have limited number of characters you can use in your buffing parade
A new FGO NP table
funny vamp ends 7 years of gacha torture
YT: FGO Gameplay , YT: FGO OST, Twitch FGO Gacha, Chaldea Archive Project - Complete
Finn can work as a tank and contribute with his 3 A cards while Astoflo just blows unless you stick an NP CE on him.
I have enough trouble filling the buffing parade as it is
although I guess it's better than it was before... around nov last year
Sumanai is actually a Servant that you can use. Not good, but you can use him.
Stheno is literally just a skill that takes up a servant slot.