im experienced lock play, this is the best possible build for putting on dots and life draining
a couple talents could b echanged around like if u want improved drain soul , that works too

but start with affliction side first, this is the most dmg u can get out of ur dots

if u plan to lvl, get a group of around 4-6 guys lay dots and run around and they should die

or if ur killing 1 mob
dot him up - life tap -- life tap - life drain and u should be at full health/mana (when i lvl'd this way, i rarely ever had to wait to regain mana or health)