I am new to mobafire one of my first guides and my english is not so good but i hope you like it

Armor pen is a must need for him quints and marks + your black cleaver will help you a lot when taking tanks down or even squishy chars
attack speed seals will help u a lot in early game because Renekton base attack speed is low
Cdr glyphs will help a lot on your Cull The Meek will make it even more spammable

I prefer Exhaust and Ignite
Exhaust helps you a lot to get enemies running away and Ignite to burst your dmg and lower heal
but you can take Ghost + Exhuast too its a good combo
you just need to have Exhaust

Start up with a Doran's Blade or a Doran's Shield your choice depends if you are playing agressive or defensive
than get The Brutalizer asap because it will burst your dmg and help on your CDR
Yomuu and Infinite edge are next itens both are awesome the activation of your Youmuu's Ghostblade + your ult and no1 escapes and Infinity Edge to burst up your dmg
Black Cleaver is also a good item because your Ruthless Predator with 50 fury will full stack it and increase your dmg , also a good item vs tanks and will improve your attack speed
Frozen MalletGood item wont let enemies escape and will burst up your life
The Bloodthrister Madred's Bloodrazor Guardian Angel 3 last items optional
choose any of this items depending on the enemy team and how is your game going
if you feel you die too much go for Guardian Angel will help you to get armor and Mres an the revive
if the enemy team has many tanks go for Madred's Bloodrazor with Ruthless Predator it will proc 2 times ( 3 with the 50 fury bonus )
if you are doing good enemy team dont have many tanks and you dont die too much go for Bloodthirster it will help you to 1v2 or even 1v3 the enemy team the bonus life steal + attack dmg will help you a lot

Play carefull until you get your full combo and after this start nuking people until you think you are able to kill them
Try to take a solo lane ( not mid ) will help you level up quick and farm a lot
after you get your ult you will start pwning people so easly u will not even see them going down

Thats it hope you enjoy it because Renekton is an awesome champ
good to be played funny and usefull for the hole team



sorry bout the english


Good Luck

Have Fun