When a ship uses the Tier 5 ability the ship cloaks after 3 sec and stays cloaked for 5 sec. BUT you can see the ship cause it has that romulan insignia outlined and marked ontop of it, so you can determine where it is at most times.
To pull off the tier 5 ability and time preventing being destroyed requires timing and almost prescience. Though its not unusual if someone does manage to pull it off, though its only every 10 mins.
The 10 min cooldown does seem right.
The reason I didn't name the guy or accuse him of hacking was because I wasn't quite sure of what was going on. I know that 0% doesn't always mean 0%, so maybe I was just kind of assuming that torpedo hits were finishing him off.
One of my general complaints with the game has always been that it's difficult to tell why you're failing. If you screw up, you're dead instantly with no real feedback about what caused you to die or what you could do better. And a lot of times when everything seems like you should be winning, you just can't make anything affect your target.