I've been working on Reg builds like this too. They are pretty tough, but the main strat to stopping them is to crush them in the early game. In the early game, these builds are weak, and have extremely low damage output. If you shut them down in the early game they are screwed. That's honestly the only way I think you can beat this build.
I like this build for it's simplicity. Usually, all of your skill points will go into Angel, maim, mark of the betrayer, long range, and Enhanced atributes (to get high dmg and dmg speed)... it relies heavily on creep killing (because of Angels AOE), and acquiring items. Best items (in my opinion) for these kinds of builds are Mageslayers and mana regens (since you need the constant mana for Angel). Later on after maxing the above atributes its all a matter of choice and situation what other skills you would like to acquire.
SO basically, deny them creeps in the early game and dominate the flags and you will beat them. However, if you let them get too much gold, and free time, you're screwed.
