If you're getting attacked by wraiths, it seems likely you're going into the swamp at night. There's a game hint that actually says something like, "It's generally a bad idea to venture forth at night." Everything gets much, much more difficult at night. There are more mobs, the mobs are higher level, and like you found out with wraiths some mobs appear that are not even present in daytime (or at least much rarer). It is possible to get through swamps at night, but I think you need some more experience in the game to do it. Hang in there, you can do it. Just stick to daytime runs for a while.