A poor choice of words mate. To prevent is not to cure and a counter is a cure to the repulsion outbreak. Once its hit then there is very little you can do at which point to will suffer heavy looses that can make you loose the game before u adapt your fleet composition.

A prevention is of-course massing bombers, using fully researched subverters and overseers. 

You know, back in the old days, you know, before Rebellion, one countered repulsion with LRFs or bombers....

Some things never change...

Guys cmon there is nooooooo counter, you are literally are dooomed or have to jump. The amount of "o"s represents the futility of trying to find a conventional counter.

The obvious choice for the Guardian/repulsion counter would be to micro a Vasari Kortul with weapon jamming ability toward the offending ships, jam weapons when in range and then stage a timed attack with other, faster ships. 

As long as no flak ships, or other more powerful cap ships were in the area, this would be a good tactic to use against Advent cruisers with spacial abilities.

Now, what to use against a Vasari egg at say, level 5....Hmm..

HAHA

another troll like this forums needs more of them