--Background Story--


Slicing through armor with the greatest of ease. Whirling, dancing like a dervish, swiping foes with a flick of the wrist. Poetry in motion, slashing enemy upon enemy in the blink of an eye. Yurnero seeks perfection. Seeks to become one with his blade. All to fulfill his destiny as the unstoppable Juggernaut.


-Why Pick Juggernaut?--
Easy killing? Juggernaut. Easy first blood? Juggernaut. Easy late game? Juggernaut. If your wants don't fit that, you shouldn't be picking Juggernaut. Though people think he can be a carry, that's not what you will be playing most of the time. You'll be always Bladestorming and Omnislashing when you can, so you won't be causing DPS. You are a burst-damage (someways weaker than Nerubian Assassin, someways stronger).

--Knowing your hero--

Yurnero
Strength
20 + 1.9
Agility
20 + 2.85
Intelligence
14 + 1.4

Advanced Statistics
Affiliation: Sentinel
Attack Animation: 0.33 / 0.84
Damage: 44 - 48
Casting Animation: 0.3 / 0.51
Armor: 3.9
Base Attack Time: 1.7
Movespeed: 305
Missile Speed: Instant
Attack Range: 100 (melee)
Sight Range: 1800 / 800

--Knowing your Skills--

Blade Fury

Causes a bladestorm of destructive force around Yurnero, rendering him immune to magic and dealing damage to nearby enemy units.

This is your bread and butter and your total guarantee that you will get a first blood IF you can control your hero. Deals MASSIVE damage on lvl 1.



Healing Ward

Summons a Healing Ward that heals all nearby allied units' life.

Pushing a lane and dying? This will help. However I do not level it up before lvl 10, because you will be needing to get bladestorm and status, and your mana pool is very low.

Blade Dance

Yurnero's cunning blade gives him a chance to deal double damage on each attack.

Description unneeded, it gives you a chance to crit.

Omnislash

Yurnero moves around the battlefield, slashing many enemies. Yurnero becomes invulnerable while Omnislashing. The search area is 450.

Your final blow, with chance of double kill/triple kill. You can also use it when 1x1 (landing all hits on one hero) or 1x3 (three low lifers, chance of triple kill) which makes this ult very versatile.

PROS AND CONS

Pros
*Very high growth of agility
*Acceptable growth of strength
*Two burst damage skills
*Attack animation is low, making it easier to deny and last hit

Cons
*Very low mana pool
*High mana requiring skills

Skill build
Level 1:Bladestorm
Level 2:Status
Level 3:Bladestorm
Level 4:Status
Level 5:Bladestorm
Level 6:Omnislash
Level 7:Bladestorm
Level 8:Blade Dance
Level 9:Blade Dance
Level 10:Blade Dance
Level 11:Omnislash
Level 12-25:Blade Dance/Statuses/Healing Ward

Explanation
Since you started your game with a RoH, you have basically no mana. Statuses will give you an extra boost until you can farm two-three Wraith Bands. You may think this is useless, and level up Blade Dance on level two. Two things you should notice though, are:
One - your damage is useless on level two, so Blade Dance won't be doing more than 100 damage with 16% chance. Pitiful.
Two - Two levels on statuses enables you to Bladestorm and Omnislash (one after the other) WITHOUT any kind of mana regen/statuses ITEMS.
It is your decision, not mine, however, to choose the skill build.

--Strategy--
Early Game (levels 1-6)
Items:
THIS is the ONLY item you need for the WHOLE early game. Farm as fast as possible, and turn it into a perseverance, which will later turn into a Battle Fury. Play aggressively, and when able, try to go for a first blood. When you have level 6, if first blood hasn't gone out yet, you should be the one doing it.

Mid Game (levels 7-15)
Items you should have by the beginning of level seven:

x2
(if needed)
Now is your time to start shining AND killing! You should be farming like crazy by using Bladestorm to clear the creeps, and you should join every gang possible. You should be DESTROYING enemies that face you alone. Don't try to go and take down two heroes by yourself: always gang with someone.

Late game (levels 16-25)
And now we see your core items (or at least good items):

x2 (dispensable later if slots needed)

(if you don't carry some of these with you if you have slots free, you are a fail DotA player, and should stop.)
These are basically your core items: Battle Fury has great synergy with Juggernaut's ultimate: besides being able to clear a full wave of creeps with just one critical, you can clear all of the creeps and not waste mana Bladestorming anymore, so you can possibly use the extra mana on Healing Wards and besides, you don't much more than that. Below I will be putting some luxury items, some late games "must-have" and refused items.

Now the team fights are occurring! Stay with your teammates ALWAYS, and NEVER go out by yourself. That pretty much sums it up.

Situational Items
You have loads of burst damage, but what good is it to carry "Focus me or I will kill you" on your head at all times?
What better than giving out 125 surprise damage and completely destroy the enemy?

Must-Haves (if you think a Must Have is part of the core, I don't think that way... for me, Core is what items have the best synergy with your hero...
Kind of obvious, 30%IASP, +60 Damage, +30 agility and 30% Evasion.

Some MS increase, some IASP, and some damage and orb. You could use that.

Rejected items


LOLGOSH YOU SHOULDN'T BE NEEDING LIFESTEAL!!!!11!!!!
and principally, looking from ALL ANGLES, it DOESN'T help you.
If you want a lifesteal, make a Satanic!!!
+5 Aura armor: Useless, you are magic immune with your first skill and invulnerable with your last skill while they are out.
16% Life steal: 4% heal from ward > 16% Life steal. If people focus your ward during team fights, they have something wrong.
+0.8 mana regen: Perseverance > aura.

Summing up
Juggernaut is a great hero and carry, you should try and pick him whenever you feel like you might need burst damage to kill lots of heroes. I principally like him for being able to deal great damage.