Traveling through the Omega 4 relay
Mass Effect 2
Countless ships have attempted to travel through the Omega 4 relay since its discovery, and not a single one has made it back, save those of the Collectors. Some think that Heaven itself is on the other side. Others believe it simply poops travellers out into the middle of a black hole.
The truth is much more practical—it leads to the Collectors' headquarters, and they're the only ones with the proper technology to get through it unscathed. The Normandy makes it through intact only to be accosted by the very Collector ship responsible for its destruction (and Shepard's death) two years prior. But if you've upgraded the Normandy's guns to their full potential, that son of a bitch is in for a sweet, sweet surprise.