You Should go for 6 attack damage glyphs and 3 armour glyphs if the enemy team is full ad.

Clearing jungle camps are very quick due to the AOE damage of your hydra.

At full build Rengar has a huge potential to 1v5 the enemy team. Your Hydra will provide all the aoe damage and an empowered q should be enough to put an adc to less then half health. As Rengar if you get stunned then you are likely to die however rengar is very mobile so you can jump in with his ultimate and flash out or stay in if you want to 1v5.