Slark, the hardest hero to lock down.

Introduction

Little known to the inhabitants of the dry world, Dark Reef is a sunken prison where the worst of the sea-breed are sent for crimes against their fellows. It is a razor barbed warren full of murderous slithereen, treacherous Deep Ones, and sociopathic meranths. In this dim labyrinth, patrolled by eels and guarded by enormous anemones, only the vicious survive. Pitched into Dark Reef for crimes unknown, Slark spent half a lifetime without kin or kindness, trusting no one, surviving through a combination of stealth and ruthlessness, keeping his thoughts and his plans to himself. When the infamous Dark Reef Dozen plotted their ill-fated breakout, they kept their plans a perfect secret, murdering anyone who could have put the pieces together--but somehow Slark discovered their scheme and made a place for himself in it. Ten of the Dozen died in the escape attempt, and two were captured, hauled back to Dark Reef, then executed for the entertainment of their fellow inmates. But Slark, the unsung thirteenth, used the commotion as cover and slipped away, never to be caught. Now a furtive resident of the carnivorous mangrove scrub that grips the southern reach of Shadeshore, Slark remains the only successful escapee from Dark Reef.

Sup guys!
This is my first guide, so if there is anything that can be edited or added please let me know.
I've played Slark in over 3000 matches, and my MMR is currently in the 4.8k to 5.2k, so I'd say I'm quite familiar with this hero.
Now, most people ask why I play him for so many games, and the answer is simple to me. I like his Versatility as well as his dynamic playstyle. Slark requires good knowledge of the map, as well as an awareness as to what's going on around. (I strongly suggest looking at the minimap every couple seconds/minutes so you can see who you need to gank)
Alright, enough of my intro, let's get right into the guide!

Pros and Cons

Pros

Hard to kill
Great escape mechanics
Strong ganking (ez kills)
Annoying as ****

Cons

Bad starting game
Depends on Essence Shift
Weak without Essence Shift stacks
Low Mana Pool

So, when can you pick Slark?
Personally, I pick him every game (don't recommend unless you feel like you can do good with him)However, I think that you should pick slark when you need a carry who can escape easily and who can gank supports easily. Slark doesn't do well in teamfights, so stuns or disables are a pain in the ***, which is why you need a BKB or Linken's.

Items

Starting Items:

Stout Shield: Standard. Blocks damage and is needed for Slark, since he is relatively weak in the starting game.

Tango: Also another standard item. Provides Slark with early regeneration, he doesn't do well against other heroes until level 6, so make sure you have tangos to regenerate.

Mango and Branches: Mango provides good HP regen, and branches have nice attribute boosts. I buy these for a Magic Wand later on.

Core Items:

Power Treads: Boosts HP, Mana Pool, and Agility. I usually keep this on Agility, as you deal more damage and move a bit faster. What I like to do is to switch to INT when you activate a spell, let's say Dark Pact, and switch to Agility as soon as you can. This makes it essentially cheaper in mana costs and your attacks deal more damage.

Aeon Disk: I actually started using this a couple weeks ago, and it's working amazingly. The HP and Mana that comes is great, but what's better is it's passive. If you're stuck in a bad situation, this item can get you out. Let's say your ult's on cooldown. The passive makes it so you take no damage, and you can Dark Pact and Pounce out. Easy

Linken's Sphere: Great because of the attribute gain, as well as HP and Mana regen bonus. What's even more amazing is that you can block targeted spells every 13 seconds. This works with Aeon Disk as well, so you can escape.

Silver Edge/Shadow Blade: This item is what makes Slark annoying and a ganker. Use it to sneak up on enemies and hit them with that JUICY +175. Can also be used in a pinch to escape if the enemy has no detects. I recommend just Shadow Blade most of the time, but if you're going against like a PA, get Silver Edge. It'll **** her up.

Black King Bar: Since Slark is weak against disables, this item will power you up and make you nearly unstoppable.

Situational:

Echo Sabre: Pretty good on Slark. Hits them twice and grants bonus stats as well as damage and mana regen. Use this if you feel like you need more damage.

Silver Edge: Explained above

Hand of Midas: Adds 30 attack speed, which is pretty good. Helps farm faster and for bigger items.

Sange and Yasha: Good item on slark. Provides good attributes and movement. The maim effect is great as well. Use when there's a fast movement hero that's hard to lock down.

Luxury:

Eye of Skadi: Really expensive but also really good. It slows them down, making it easier for you to steal attributes and attack faster and harder.

Boots of Travel: Isn't really needed since you're already fast, but can be used to TP home or onto another creep. High movement speed helps chase down fleeing enemies as well.

Aghanim's Scepter: Can be used if you want. Not needed, but the 30 second cooldown for ult is invaluable. Can also be used to hide your allies, which is a good ability.

Monkey King Bar: Use against evasion. Grants accuracy as well as dealing bonus pure damage.

Playstyle

Early Game: Slark is very weak in the early game, with low HP. I recommend using him in the safe lane. In early games, try to get your farm up and purchase Hand of Midas if you can. I only get it before the 12 minute mark. If you can't then don't get it. It really only helps with extra gold, so it isn't a core item. Just play safely until you get your ult, then you can start ganking and try to get the Shadow Blade:

Mid and Late game: In the mid and late game, keep farming but also start ganking. Don't gank tanky heroes, because they are a pain in the *** to solo kill. Try going for the fragile supports who have little to no disables. Simply walk about and hit them. As soon as you do, pounce and dark pact. Try to get in as many hits as you can. The point isn't to necessarily kill them, but to take them out the teamfight that'll happen later. By doing so, you are gaining stats as well as taking out the supports. Slark has strong kill potential if he has enough stolen stats, and once you do, you can start joining fights or just solo killing everyone.

End

Thanks for reading my first guide on my most played hero.
Let me know if there are any adjustments I can make, and if you have a suggestion, let me know as well!

I hope you try Slark out, he is a fun and an annoying hero!