My character is a harbinger, so I think I can speak halfway decent for a Dreamkiller. They are a lot alike.
I put one point into Empathy for the lifeleech to start out with. Later on I went for trace of wrath at the high end-the skill disruption and especially reduced target resistances would be killer for a Dreamkiller since you rely on poison, pierce, and bleed damage. So as you move onto epic, think about maxing that trance and using it exclusively.
I would suggest that you look into Distort Reality/Temporal Rift down the line. It's fantastic crowd control on a pretty reasonable cooldown. Maxing Premonition and Temporal FUX also seems like a must-do for that kind of build.
I would think hard at first about putting a few points into a few key, focused skills while still throwing a good half or so of your skillup points into mastery skillups, as the hit point,DPS, and OA/DA boosts are really nice. I had my main mastery (Dream) maxed out when I reached the end of normal, and my secondary mastery maxed in the middle of epic or so.
I would go with one-pointers for skills that really offer a lot with just one point. Don't spread stuff too much out, and remember that you need the following to survive as a dual-wield/2Hander:
A) A good crowd control spell, preferably on a low cooldown so as not to slow you down too much.
B) fast burst DPS against a single target when you neeed it. (like a right click for massive damage ability, ala lethal or phantom strike).
C) Good offensive/defensive ability scores (OA/DA). Especially DA, that alone can make the difference between a wtf impossible fight and SNORLAX GO.
D) Pierce resist whenever you can get it. It's well itemized on shields, not so much anything else. On normal difficultly, archers are very nasty foes.
