I don’t know if this has been asked yet (if so, then sorry):
If servants can materialize and de-materialize, how come they never use it for combat like
Nightcrawler character in
X-Men do? The principle is almost similar, right? Is there any ‘rules’ for it?
If they DO use it in combat (not spying, etc), please give me some examples/proofs (either from the animes or games).