This is a Doomsday build for CoastCity Jungle! You start with the basics Marauder and The amount of health potions you feel confortable! i usually get 5! 

First you will upgrade your marauder to maximum, to fast clear jungle. for second item grab the Hawkman's it gives you 400 HP for only 1k credits, pretty cheap right? and it's refundable! Ok! now we need to focus on how are we going to be efficient ganking and tower diving! this is where Batman's belt comes

Batman's Belt gives everything you need, Atkspeed and movespeed to combo with your W, and being faster also helps you to land you E correctly, it also gives you CD and a decent Health more CD you have more you can throw your opponents into the ground!

At this point of the game, you need a way to kill enemy heroes 1on1 so you need survivability for taking Doomsday Device and the Relays without fear.

Claw of Horus help you with this, it gives you Atkspeed atk dmg/armor and the 2 awesome passive skills:
1 kinect armor steals armor from your opponent really fast to achieve 5 stacks cuz of DD high atackspeed
2 Desperate Strenght: 1atk dmg every 2% missing health this also helps because when you loose around 50% hp you still have more HP than the average heros, so you'll have +Hp and +Atk and this can turn your fight around.
At this point teamfights start to come around and you need to climb your way to deal as much dmg as possible.

!DOOM! Spear of Destiny: 50 power armor! will help you a lot against heroes like Green lantern;Shazam , and the Critical dmg really hurts , 15% looks low, but it's not with the high atkspeed we stacked so far, crits will occur often! ( have i said doomsday crits really hurts? ok) and least but not last the Wonderful Passive: your high Hp around 3.5~4k will give you an awesome Attack dmg! this item is perfect get it!

It's time for you to sell your Hawkman's Harness and buy Fragment of Mogo: Almost same Health pool + a lot of Power armor and CD, it really helps! you can do this before if you the enemy's power dmg dealers are too much feed.

The 6th and last item is wide open, you can go for:
Lobo's chain: gives you HP ( more hp= more dmg cuz of Spear),++Attack dmg and a decent slow if stacked at 3!

Joe chill's revolver: +Crtical dmg , lots of dmg and critical chance, get this if you think you are already tanky enough!

If you need to get more tank get this:

Suit of Sorrow : good against heroes with a lot of attack dmg/speed ( Gas.Catwoman,Gas.batman,Nightmare.Bat, Cyborg etc...) (100atk armor is awesome)

Ra's al Ghu'ls Robe: if the enemy team got both attack dmg and Power dmg feed, but since you already have power dmg protection from Fragment of Mogo, only get this if the enemy's AD carry is not epic feed. otherway is really more viable getting Suit of sorrows to kill him with reflect.

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This is it for now guys! any doubts or suggestions post 'em and i'll answer as soon as possible!
 hope you guys like this build as much as i do!

Good Luck n' HAVE FUN!