at rank 3 your tormented soil will 1 hit minion waves if you follow this sequence. With this you will be able to out push any match up if you focus your mana on farming, only using dark binding when the enemy champion leaves an opening or to avoid a gank. if you do this your clarity will be up when you get to about 25% mana. As long as you do not needlessly waist dark binding you should never have to back except to buy your boots and soul stealer. Since you can out push and out last your opponent you should be able to down your turret between 13-20 min depending on your match up. Once this happens you are free to roam and gank easily building your stacks. As long as you are not ganked to much you should be at 10+ stacks and have your death cap by lvl 13. If you are able to achieve this you will snowball once the laning phase ends and dominate the team fights.

if you are facing a more mobile team i tend to favor morello's evil tomb over void staff to give me that extra cool down reduction to help get those dark bindings off more often. The other thing is to take flash or ghost instead of ignite. The reason i take ignite is for the +10 ap when it is on cd as well as using it to either kill or simply force my opponent to back therefore increasing my laning advantage. If you are not confident in your ability to avoid ganks, take flash otherwise take ignite to keep up the pressure. Feel free to take a skill in black shield if you are laning somebody with a stun such as annie or malzahar, just make sure you don't sacrifice a point on tormented soil.

the good part of this build is that you hit really hard, and if you become skilled with your dark binding you should be able to win any 1v1 match up. with your dark binding hitting so hard anybody hit by it is a guaranteed kill mid to late game weather or not you finish it or by a team mate. As with any offensive build you loose your durability, which morgana can so good at with a support build. However with your black shield, dark binding and shackle you have plenty to get away with. I have often won 3v1 with this build.