I've got a history of downplaying my characters. I'm using Mordred as a tool in a way. If players drop out, and they do usually I've completed a total of two roleplays in over 10 years, I can use a stronger servant to defeat an enemy in some way. More so Mordred is also a rather one trick pony. She hits hard, and she hits quick. She also has a big laser. But that's all she does. She's not say Raikou who has the following spread. 



[hider=hider for statline]
A[1]
B[1]
D[1]
A[1]
C[1]
A+[1]
[/hider]

On top of eternal arms mastery, and the ability to clone herself to use weapons from her own story's group. Not including a similarly large streak of lighting, a bow and arrow, and kintoki's axe. I'd say as a DM tool Mordred is about as baseline fair as I can get. She has a limited range of movement, a powerful super, and a solid skill line however she won't be taking away anyone's thunder as she can't spam Blood Clarent Arthur, nor can she cast spells, or fly. A tank with good damage output that won't eclipse the party. 

And yes victories should feel earned not given in my opinion especially when victory is more or less guaranteed anyways given the pve nature of this roleplay. If any of this upsets you, you're free to withdraw your interest. I am also open to suggestions on what a proper servant that serves my apparent rules while also allowing me to get over the hump of killing off a servant due to someone's prolonged inactivity, or ghosting.

On subject of why Medusa is iffy: Once again a flying based servant brings up the question as me as a dm of "ok how do i counter an opponent who flies? And do so consistently?" Generic enemy skeleton/soldier archers constantly seems like a cop out, and constantly having to have an archer around ruins the chance for variety. Medusa specifically is also capable of stunning individuals with lower magecraft resistance, and royally mess up anyone within her blood fort if she can manage to set it up. Furthermore she has mystic eyes, independent action, divinity, and magic resistance. All of those skills do make her a significant servant even without Bell.