Kayn is one of the few champions that you can blind pick with very little to worry about. Thanks to his adaptability, he has an answer to everything. Here are a few situations you will commonly find yourself in, and which form to pick to rise to the task.

★ Your team needs a tank ★ They have two or more tanks ★ You have a bad matchup in jungle (e.g. udyr)] ★ Your team needs some hard CC

★ Your team needs more damage ★ They have four or more squishies ★ You have a good matchup in jungle] ★ YOU WANNA ONE SHOT PEOPLE

Ganking with Kayn is totally different from any other jungler, all thanks to your E - Umbral Tresspass. Additionally, your mobility is much higher in both forms than almost every other jungler as you can path both through and over many different walls, allowing you to take a more straight line to your target. A few key tips about Kayn's mobility are his ability to hop walls and extend the range of his E with his Q. Kayn's Q has a very limited range, however, if the range extends over a wall you will hop over it. It is not like flash where if you get over halfway you flash over.

Kayn has quite a large range of jungle pathings available to him thanks to his excellent early game clear and sustain. The clear most people hear about is his raptors start: Raptors -] Red Buff -] Krugs -] Wolves -] Scuttle This works, yes, but against a strong early jungler, if you go to contest the scuttle after doing this clear, they will whoop your *** cause you're on about two thirds hp. This is why most of the other clears involve getting a leash. Here's my personal favourite: Red Buff (get a leash) -] Krugs -] Raptors -] Wolves/Blue Buff -] Scuttle This clear gets you to scuttle on near full hp and gives you a decent chance at fighting scuttle because most other jungler's first clears aren't as healthy. Additionally, this clear suits powerfarming as you can quuckly clear the remaining camps and as long as you're back to krugs 2 minutes after you first clear them, they will respawn and be worth more xp than the first krugs did. Since the Season 10 jungle changes, starting blue buff has become viable again! Since clearing Blue Buff, Gromp, and Wolves will now give you level 3. This gives you the option to do Blue Buff -] Wolves -] Gromp -] Look for a gank -] Scuttle or Blue Buff -] Gromp -] Wolves -] Red Buff -] Scuttle
Karasmai has made a great video that shows some super important tricks to help you do all Kayn clears faster and healthier.		Play Video

Conqueror Runepage
Primary Runes

Conqueror gives Rhaast fantastic sustain in addition to his already strong lifesteal. On top of this, the additional true damage combines nicely with Rhaast's %HP damage, allowing you to really rip through tank's health bars.

This rune is great for Rhaast as it enables you to be more aggressive when diving tower, as you can tank and extra couple of hundred hp worth of damage as long as you get the kill beforehand.

Crowd Control = Death. This reduces the duration of hard cc allow you to output more damage, and since you heal from all your abilities, this will keep you alive for much longer. Additionally, quite often in teamfights you will want to use your R to reset your Health as it has MASSIVE healing. However, if you get enough to where you want to use R then you get hit with some CC, you are most likely going to die before you can get your R off. Tenacity helps to mitigate this somewhat.

Most of the time as Rhaast, your aim in teamfights is going to be; to dive the backline, knock the squishies up, cause a bunch of damage with your skill rotations, then ult a tanky enemy to reset your HP once you get low. Last stand will greatly increase the healing you get while low and will help you clutch more teamfights and skirmishes in general.

Secondary Runes

Sudden Impact is a perfect runes for Kayn as it activates with your Q and the lethality gives you more burst potential, especially against squishier targets.

The additional healing Ravenous Hunter gives rhaast meshes well with his kit, it provides an additional 14% spellvamp on top of your rhaast passive which can often can be the difference between living on 100hp or not at all.

Electrocute Runepage
Primary Runes

Electrocute gives you a large amount of additional damage early, and provides a lot of burst late game. The extra damage early game makes you more viable in early skirmishes and gives you some kill pressure as people often understimate Kayn's pre-form damage.

Sudden Impact is a perfect runes for Kayn as it activates with your Q and the lethality gives you more burst potential against squishy targets.

This gives you some nice bonus AD which is always welcome. Can also be swapped out for Ghost Poro if you want more vision control

This rune synergises well with the Shadow Assassin, gank heavy playstyle, as the additional movement speed allows you to traverse the map faster, allowing you to react and rotate to what is happening on the map faster.

Secondary Runes

Celerity, like Relentless Hunter, allows Shadow Assassin to move faster giving you more overall map pressure.

Water Walking gives Kayn some nice bonus damage for contesting the first scuttles. It can be replaced with Gathering Storm if you are confident with your early matchup and want more late-game power scaling.

Or

Gathering Storm, while giving a slightly weaker early game compared to Water Walking, gives Kayn much greater late game scaling.

To summarise, Kayn is the smart*** that has an answer to anything and everything. While also being incredibly fun to play!

Also, as long as you can get down one key thing, Kayn goes from being a "hard" champion to one of the faceroll for a win champs...

Master your transformation.

If you can consistently reach a 10 minute transformation (or earlier) you will find yourself outscaling enemy junglers even if you're behind by a few kills this means that although Kayn is a weak early-game champion, you cannot power-farm before your have your form.

Aim to do your first clear, look for a gank, clear your 2nd raptor and krugs and aim for another gank.
When you reach level 6, you want to look for a full engage against the enemy that grants you your desired orbs.
Remember that the later into the game you go, the more orbs you gain per hit on the enemy. So a full engage at 6 minutes is worth considerably less than a full engage at 8 minutes.

Thanks for reading my guide!

If i've missed anything or you have any advice please leave it in the comments! I'll try and update the guide to be as helpful as possible ASAP.