This build not only creates a powerful right-clicking demon, but it also provides durability where needed. Forget those negative armor builds. Sure they might work in low mmr, but most of you aren't aiming for pub stomping in low MMR because this build isn't solaly intended on doing just that. It creates a well-rounded mid-lane hero that can initiate/carry/push/support. YOU NAME IT. I use variations of this build against 4-5k mmr mid laners and I win almost always.
Decent mind tricks you can play on your opponents during the laning phase is to re aggro the enemy creeps before your creeps get into cs range. This forces him to either miss the cs or move up towards your side to secure the cs. This allows you to 1. Harass him 2. deny the creep. During laning phase, when the creep wave is too far to safely cs (ganks, global presence) make sure you stack the two jungle camps on your side to farm when mid lane is either pressured or pushed. This secures your farm and increases your soul count. From here on in, just keep the enemy hero pressured, take the tower(if possible) and work towards teamfight oriented items (mek, BKB)
If you were harassed or just simply lost mid, use mid game to boost your net-worth by raze farming the jungle as quick as possible. SF is great hero to make comebacks happen with. When you're comfortable enough to fight i.e you have the appropriate items to team fight with, you can smoke gank to start the push at an advantage. Use the advantage to either take objectives or to take rosh.
Shadow Fiend is a great hero to scale into late game with. He has incredible damage output and with the right items, can survive any fight. If you are lacking the necessary items to fight in the late game, use your natural damage output to split-push lanes safely. This way, even if your team loses the team-fight, you can salvage a t2, t3, or even a racks or two. But honestly, follow my build and with the right skill, you won't have to split-push. Create the right initiations on the proper ground elevation (highground vs lowground) and win the damn game already !!! :D