Should I grail Carmilla?

If you love Carmilla as a character, then I would grail her. Her final ascension art is wonderful and she has a good anti-female niche (even if it is surpassed by Jack the Ripper)

I wouldn't grail assassins for gameplay, they have 0.9x damage multiplier so they are not very useful outside of class advantage. Carmilla is also quick-based, which isn't as effective as Arts or Buster until we get Skadi in 2 years. You may also get King Hassan in the future, a 5* Buster-centric assassin which will be very powerful with a support Merlin.

She's ok. The only problem with her is lack of survive skill and low damage. She has high NP gain that's mean she can throw her NP quite often. Her NP deal extra damage to female(there's a lot of female rider and berserker in game). Not that good but not bad. Grail her if you want. Oh and if you check pushie mistress YouTube you can see Camilla soloing Geotia and some high difficulties challenge for reference

Carmilla is simply the overall best SR assassin once she gets her NP interlude. She's no match for Jack or King Hassan damage-wise, but she has a bunch of utility and NP spams a lot.

Kerry is better than her when he's inside a Tamamo comp, but only inside a Tamamo comp.

Grailing makes a really-really small difference, so yeah don't grail for gameplay.

She's my main ST assassin for a year until now and i rarely borrow friends Jack or my friend ST assassins because she does her job pretty well, also my Carmilla is lvl 80 NP 2.

One thing she does that's always impressed me is, her NP gain is absurdly high and i would like to stack those ATK bonus as high as i can.

For me, i'm using my Grail for Fun and favorite servants.