Hello Everyone
I just wanted some help on the way Items work and which ones I need to build given circumstances I usually look up pro builds and just build that each game even tho I might need something else, I am also a jungler main.
I main 
and 
if that helps :D
Thanks for all your help
Item efficiency is quite complicated, and one of the slowest learning in the league. It depends on Champions, composition, and the enemy.
There are mathematically ways to calculate how good an item is, but no body really uses that in real life.
For starter, there are 2 to 3 main stats every class of champion wants, for mages it's AP/CDR, for ADC it's AD/Attack speed/Crit, for Assassins it's AD/Armor Pen, or tanks it's HP/Armor/MR.
Usually you go for one item in your main stat, and one item in your secondary stat. If there is one item that gives it all, rush it first. If you are struggling to live, build a half item/full time in defensive against your opponent. If you are winning hard, double down in your main/secondary stat.
For example on Rengar: Zhonya's or voidstaff or Rabadons Deathcap
how will that differ? like would this do more damage to different champs or will it just give me stuff that an AD build can't
here is the basic build I use for Rengar http://www.mobafire.com/league-of-legends/build/season-7-thrill-of-the-hunt-indepth-pro-rengar-guide-456075
