I recently picked up rengar and I have been having problems building him. Coming off maining Kha I have been stacking ad with a little HP. I have been able to one shot adc during mid game but I fall flat on my face late. Plz help. Also what streams/pro players/youtubers should I watch to get better at him.

Just started playing rengar, he seems to do well with tooth and then mogs then lifesteal... gets him those passives, a little bit of tankiness, then damage+survivability. If you get fed and make it to late game strong, try a Mallet for tank and slow.