This is good for a short game but for a long lasting game you may have some problems with some champions since they will have lot's of damage and this is build for dmg and hp/mana :)
You can take some hit's but should be carefull since you don't have alot of armor :)
Something very usefull is that your poisen will give alot of dmg together with fling :)
You could also buy warmongs armor or Archangel staff too get more hp and mana instead of zoyna's ring but I prefer these items :)