I actually do use these things offensively...  If I'm fighting over a neutral planet, say a Gas Giant, I will quite commonly lay a few gravity mines right beside them to act as a sudo-PJI.  I don't ever take the time to do it to all ships, but I do make sure to knock out capitals, HC's, and Carriers..  After that, I simply lay normal mines to knock out their health...  In other words, I use this all the time, if for no other reason than to hear that thing say, "I've got a present for you.."  It makes me laugh maniacally every time.  I love the Ruiner..  

Most of the time...  Later in the game, I just stop caring about mines and just start running over them because I like the explosions of the mod I downloaded the other day.  But in all reality, I think that if you had 5 ruiners or so, you could easily put them in a world of hurt via EM's or prevent their escape with GM's.  And I don't just lay them anywhere..  I actually do use them strategically...  Though now that you mention it, I will make sure to avoid putting them near flak.

I just use this tactic in a battle It was soo much fun watching their fleet go poff. A bunch of lrms were in a group and I layed mines right on top of them. 15 seconds later they were gone. I had already out fleeted them but this was so much fun watching mines do all the work for me and I bet the were pulling there hair out when it happened It is so much fun planting mines and watching them do their work in the enimy fleet.

what is more fun is when your enemy is fighting a battle at one of your planets you put mines all the way to the phase lane, then laugh at them when they want to retreat.

if they go around they lose their fleet to my fleet, if they stay they lose their fleet and if they go though the mines they lose their fleet.

you should try it some time, usually people are microing in battles too much to notice mines being layed behind them

_|~Uber

I could see that going poorly since seekers are exactly what you need to help kill them even after they phase out.

[_]-Greyfox

Emp i was playing you with mines yester day and my mine tactics do wonders. I developed it long ago its quite easy to counetr when you know its coming but if you are suprised with that and mines are microed well it works in 95% cases.

The weak point is that its really hard to micro it.

My mine tactic rocks!!!

My MINES are ready!!

You played quite well in that game.... I look at the replay to figure how you out econed me and it was pretty much I spent too much time killing a roid that was your allies when I need to expaned faster. Anyway, your mine tactic has noted by me and I will not forget it.  

@Greyfox

Your right. If you see the ruiners coming You can kill them quick with a late game fleet filled with bombers.