M/R has one DoT, Cursed Fangs. Lots of fun, but not stackable DoT, and only worth something if you have Fang Ritual running. (15 min buff)
We do have nice elite skill - Kiss of the Vampire - inflicts damage on targe, and restores up to 10% of your HP and once you get Gift of the Baron, when you successfully cast KOTV, next 2 attacks will do 15% more damage.
Pros: easy to level, no problems in PvE or PvP. (lots of fun actually) Cursed Fangs is spamable, but DoT are not.
Cons: You need cloth for mage side (stated as mage) and leather armor for rogue. Might have some problem to level both at higher level. Not easy as when lelveling R/S (same gear) or M/P (again, the same gear)