Having returned in January from a lengthy hiatus, I spent an afternoon swapping out all sub-classes and taking notes of what levels were required for certain key abilities that seem to augment masterfully. Strictly speaking for melee heavy, I made this build. I'm certain it's been conceived and rehashed in many fashions but this is my take on it.
<a href="http://www.rifthead.com/stc/zMTMwlcVzku0f00bvlsooG0RdxRgoz">Riftstalker (32) / Assassin (44) / Marksman (0)</a>
The strength of this being obvious I think, what it lacks of more concentrated direct and passive abilities from further investment into Assassin, it compensates in supreme mobility and boosting crit and damage with *very* decent up time I think (anywhere from 30-40 seconds in a minute if in the "flow").
I chose Marks as the third tree for increased mobility and a means to do at least some range if my opponent consistently succeeds in evading and stalling me.
Using this build in the proper mind set, I am porting between foes left and right, stun-locking, bursting and porting to safety if need be for any reason.
It works, very well in my experience. Granted I lack a third poison, panic button AOE confuse and strong single poison attack; however boosting/sustaining crit and damage to currently 45% combined with my maintain ability to burst quite sufficiently, it seems highly effective and versatile when needed.
Use it well ^_^