Servant, Saber.
I am Barghest, and I have come in answer to your summons.
I may not have the right to say something like this, but...
As repayment for you attending and watching over the end of Britain, I will wield my sword for you until my life ends.

servant class:

Extra information:

It takes place in Chaldea

it's your Servants and you are the Master

and most importantly, you must possess Command Seals that, when activated, will force them to do any order you want.