Forevermore

I want to make a scrapper, a katana scrapper, and combine it with a damage aura. I'm just curious what the pros and cons of each of those sets are. I know fire has a great heal, dark has a built in stealth, but beyond that, I really don't know much about the sets. Any help would be mucho appreciated.
Thanks.

Thanks for the guide Gobb, you should have it stickied, I had to look all the way at the bottom for it, and it has been a big help in my db/sr brute build.