Question

I will server you as your most faithfull slave . using serve noun form

Answer 1

Hey Dear!
________

You have asked to modify the sentence to use the noun form of the verb 'serve'.
The noun form of 'serve' is 'service. See here as to how the sentence would look like after modification.

I will give you the service of your most faithful slave.

Though we can also make it as -
I will give you my service as your most faithful slave. 
OR
I will give you the service as your most faithful slave.

But the most suitable is that I have given in the beginning bold letters.

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Any problem in understanding , feel free to ask.

Answer 2

Answer:

I will have a service for you as your most faithful slave