I'd suggest you to go for feral flare 90% of the time as it gives Rengar better scaling into lategame than Elder Lizard. Thus having quite a good synergy with the Bonetooth necklace . However in some cases the SotEL may be better for early pressures.
** Tiamat used to be a core item on Rengar but is far less needed than it used to be IMO**.
BotRK is far better on him for different reasons, it gives him AS which synergies well with eQ and the magic damages provided by the Feral Flare. Those aa hurts quite a lot :)
BotRK will help you to fight against this annoying tanky top too.
The active may as well save your life/ kill that running prey :)
I go for CDR/Mobility boots most of the time. Mercury boots are quite interesting too. Again it depends on how the game goes and what you need.
Youmuu's Ghostblade is an absolute core item on him. It is really useful when it comes to your ult since it gives you the MS to catch those flying carries.
So the usual build order is the following (each number stands for a recall):
-
& 4
. Nothing big here.
-
&
OR
& 1 or 2 wards
-
OR
& 1 or 2 wards.
(You should be level 8-9 by now. Grab that
, you won't lose stacks)
-
OR
(depending on what you bought previously)
-
You should have around 25-30 stacks on your Madred by now so grab the
.
-
/
(the one you didn't bought previously).
-
Go for tanky items from now on. You don't need more damages items since both teams should begin to regroup and you won't survive those TF if you don't have that
:)
This build order is the "general" build order. But depending on how the game goes you may need to buy tanky items earlier. Especially if you're behind. DON'T BUY THE WRIGGLE LANTERN IF YOU DON'T HAVE 25-30 STACKS. The item is simply not cost efficient without the feral flare evolution and Rengar need those early damages to be efficient. You may want to take the last whisper if you're far ahead. But it makes you really squishy and at this stage of the game you don't want to give a shutdown. The W is interesting but won't make you last that long. Unlike many other assassins Rengar doesn't have any escape. Thrill Of The Hunt isn't an escape.
Hope this help :)
Enjoy Rengo ! :D