My understanding of the current state of Rengar is that you build for damage and explode squishies in fights and split push on the side. He does a lot of damage to towers, and the only people who can survive his burst tend to be the Crowd Control tanks for the enemy team. If Malphite is busy trying to stop Rengar from killing a tower, he is not malphiting your carry in the 4v4. If anyone else is sent to stop you, you kill 'em. Boots of Mobility seem to be popular for helping Rengar rejoin a fight, since he'll be more mobile in than Malphite or another tank would. It's got decent synergy with Thrill of the Hunt, allowing him to rapidly access the back end of a fight and cleanup.
I've also seen Merc Treads/Ninja Tabi combined with Distortion. Combined with Teleport and the Mastermind mastery, you can get Teleport down to a 3 and a half minute cooldown and Flash down to a 3 minute cooldown. Although that requires 7 points in the Utility tree, and I'm not convinced Rengar cares enough about Utility even with the potential +3% lifesteal. --- http://i.imgur.com/7Wah6.jpg I'm actually incredibly overly passionate and...whats the word...viscous? - EltoniaX
I did it recently it and went like 37/10 It was one of the funnest games i played in a long time i wouldnt say it wins games because you dont want to win the game, you just want to kill the enemys in one shot
my build was bt -> divine -> cdr boots-> ie then 3 more bts becuase i was so fed and had no idea what to do ignite/ghost to catch up while you ult --- Friendly reminder to get karma on your alts