First i buy mejals and then i start to pwn at lvl 6 once i get black shield. Over all at the end of u power up and keep getting kills i got on soul shackles to be 350(856) magic dmg and the first one 350(346). this build has worked for me rlly good so give it a try
*Note: Buy mejals only if you have a good team and think you can get some kills. Only works if you kill and not get killed

Early game: get the move that stuns. I buy tome for ap for extra boost. Once I have that just go with a teamate and wait for time to kill. When fighting another champion. Hithim and when he is running away shoot the move that stune on front of him so it can hit him or were u think it will hithim. Just scare them at beg. Oce u learn the puddle move, lay it on the monstersto get all the money,

Mid game: by now u should have mejals and the boots with magic penetration. Get rod of ages to power up and the extra boost. Try to do many assist or kills to power up ur mejals. Get void staff

Late game: by now u should be close to end of game. If done correctly u should do hvy dmg. I personally use the stun first. And then the puddle to reduce the magic. After that I use soul schalke and they should be pretty much dead if now ur. Stun should be rdy for use again.
Gl. Rate me or ask me questions if u have any:)