Building Poison Ivy to be A huge threat in teamfights is not really her intended role. This guide will show you how I personally level all of Ivy's skills and what items I get. So first off this guide was made on the Gothams Height map, but works on the other maps, as long as your team knows that you are not supporting.
     I start with going one level in each active ability and then first leveling her Root Strike for the most damage early along with the extra knockup duration. Then after leveling her ultimate at six I finish leveling root strike before I put another level in both her Thorn Sheild and her Healthy Glow(Passive) for more overall survivability. After leveling her ultimate again at ten I max out her Blow KIss before leveling her ult the last time and finishing her passive and Thorn Sheild in a back and forth pattern.
     The items you would get on a Poison Ivy that is not playing support seem to e limited to me. The Abin Sur's is for the Will, so that she doesn't have to go back to base after every fight. The Cosmic Staff and The Book of Eternity are for the power armor penetration. The Fatality's Energy Lance is for the amazing burst potential on squishy targets. The Starheart is there because of the PD boost that the passive gives. Finally the Neron's Contract is for the ability to go into stasis when being focused.
     To effectively play This stlye of Poison Ivy you must land your Root Strike in fights and in 1v1 sitiuations. You sve Blow kiss and Thorn Sheild in 1v1 sitiuations for when the other player first starts to attack you. Then both can be cast whenever needed. Root Strike when landed continually will allow you to kill an enemy with very little damage taken.
     The sitiautional items are if you want to have a little bit of utility and can be substituted for any items except Abin Sur's