That's pretty much a wall of good advice Dook has provided. Here's what I can add:
- Place the main in the backrow, with a witch beside him (if you have one). This way the chances of you getting hit drop to 2/9.
- Always guard your main.
- Beer up, if possible-- i.e., turn that blessing potion on.
- Scroll strategically ASAP- if you can get two or three judgement/freezings off really quick, the minions will die off fast. You want to be fighting only Servant as quickly as possible.
It's the nature of my circuitry.