I believe the way EP works in general, it is figured as a ratio of EP against one another + X percentage of total spending to get certain aspects available to view.
It's really pretty straight forward, you only have 2 ways to affect the opposition (their EP anyway), spend more than them, or run counter-espionage missions.
The biggest problem I see with MP, if the human is paying attention, They will know WHO is "attacking" by keeping track of of available EP points every turn.
If you are at war already, then that is no big deal, but in peace time, even if your spy doesn't get "caught" in the game, the opponent should KNOW exactly who perpetrated the act.