Ok, this is kind of confusing:
Player A and Player B are in the same alliance.
Player C isn't.
Player A and B both have their spies on a relic (25 infiltration ticks each)
Player C also has a spy on there, but with 75 infiltration ticks.

What happens if there is a spy battle?

I believe Player C wins during a spy battle.

Infiltration ticks of same alliance does not stack and each have their own amount...so the one with the most infiltration will succeed.

-MilanorEx

thanks, anitsu