Chaos Knight is a very strong carry/push/ganking hero. He is a late game carry which requires lots of babysitting in the early stage. Thus it is essential that he gets proper farm and support from teammates early in the game.
This build helps you to be a proper CK, feel free to modify the choice of items or skill build in this guide as they are only my recommendation. If you feel that they doesn't fit into your situation in game and you have a better solution, then why not ?
Im sorry but somehow i cant add the author's note on my pc so you may find my guide to be quite vague.
HERE'S THE DESCRIPTION FOR THE SKILL BUILD AND ITEMS

SKILLS :
CHAOS BOLT : it is a good single target stun, but it takes up most of your mana in single use. Thus i recommend you to level up this skill only once at level 2. Also, chances are there would be supports to help you stun/slow enemies to get kills or bail you out in the early game as well, so Chaos Bolt become somewhat not so useful early on.
REALITY RIFT : a great catch-up skill which you need to max out FIRST for its incrased damage, range and cooldown. Patch 6.83 onwards had been kind for CK as Reality Rift uses only 50 mana now instead of 70. This makes Reality Rift a more practical spell early on not just to harrass, but to pursuit and kill enemies in your lane.
CHAOS BOLT : though has a low chance of 10%, i recommend you to get this skill more than Chaos Bolt early on as it will give you a better experience in farming and killing mid-game. Also it has this badass sound that will make enemies back away from a moment in the lane for some reason
PHANTASM : this baby here is the main reason to why CK is such a great damage dealer and pusher. However, i recommed you to get this skill at level 10 and 11 instead of the usual 6. This is because of mana problems and 1 illusions with a chance of another extra is not that great early on as CK wont have much damage to deal anyways.

ITEMS :
STARTING ITEMS : purchasing quelling blade is optional if you feel that you are not good in last hitting. Gauntlet of strength should be bought for a later Drums Of Endurance. Tangoes is a must and clarity with a branch is just icing on the cake, you dont need to buy them if you prefer not to.
POWER THREADS : a great allround item for CK and the only boots that he should buy. Reminder to ALWAYS CHANGE TO INTELLIGENCE when casting Chaos Bolt and Phantasm.
DRUM OF ENDURANCE : great stats item for increased movement speed and intelligence for remedying mana issues for a little bit.
HELM OF THE DOMINATOR : lifesteal item to be upgraded to satanic later on
ARMLET OF MORDIGGIAN : hands down a must for CK as it gives him and his illusions steroids. ALWAYS ACTIVATE THE ARMLET BEFORE ACTIVATING PHANTASM as failure to do so means weaker damage given by the illusions and makes you less effective in teamfights.
ASSAULT CUIRASS : picking this is mostly because of attack speed only. The armor it gives is somewhat not so good as you are already quite heavily armored by your armlet and HotD. So after your armlet, it is a situatonal between AC or ♥♥♥♥♥ and Yasha.
SATANIC : once you have a attack speed item ( AC or S&Y ), you will need to get this. Satanic gives more survivability and damage to turn teamfights around to your favor.
MONKEY KING BAR : once survivability and attack speed is now good enough, you will need more damage to one shot enemies with just one Reality Rift. Monkey king bar is a good choice for countering enemy carries potentially buying evasion items or have a passive evasion skill. ABYSSAL BLADE is more recommended if no one in the enemy side is buying or having passive evasion.
BOOTS OF TRAVEL : with all your items now almost complete, there will be no more space for the all important teleportation scroll, so sell your Threads and get ♥♥♥.
EYE OF SKADI : well by this time you should reach the 40 minute mark of the game and Drums of Endurance now becomes so useless with just little stats given. So Skadi will become a mush better late game item with greater stats. You may not be moving as fast but its passive slow to enemies will remedy this problem anyways. So sell your drums and get this item instead.

Alternatively, if you choose to get ♥♥♥♥♥ and Yasha instead of Assault Cuirass, you can dissassemble them into Manta Style and Heaven's Halberd which are great combinations for CK as well.

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