Kayn gets red form from melee champs and blue form from ranged champs. However, that's not the only way you can determine how to get form. For example, if they have a hyperscale champion like Veigar and another heavy AP mage such as Lux but 3 melee champions. It may be beneficial to go blue Kayn. One shotting squishies like those two can benefit the team greatly since they have heavy damage/cc. Blue Kayn is best when ahead, if the match up doesn't look great for you you'd probably be safer going red Kayn seeing as he's slightly tankier and has more sustain. As blue Kayn you never want to try and gank cc lanes without E, you're also squishy and getting cced against fed laners is almost a guaranteed kill for them if you can't get near a wall fast enough. Red Kayn is a great frontliner, if you see the enemy team and they have four squishies you'd automatically think blue Kayn, however, if your team has squishies too red Kayn might be better. In general, it is ok in most scenarios (like 90% of the time) to go red, even if blue would have been ever so slightly better. However, going blue is only good in few scenarios since he's also squishy and can't really be 100% in team fights. if you know the game is going late choose red form unless they have all squishy characters on their team. If your team needs a frontline go red Kayn. If you are losing the game and it's starting to snowball out of hand when you get your first form just choose whatever is available because you need the power now to potentially bring the game back. If you get fed and think you are going to be able to snowball the game quickly try your best to get blue or they have multiple priority squishy targets on the enemy team go blue. Also if you have a tanky top lane and support preferably ones who can initiate blue form is also a good option. Don't forget that Rhaast's ultimate heals himself for a percentage max health of your target which makes it pretty good against tanks. Don't always listen to what your team says about your form because you're the one who's going to master the champion, try and figure out what does and doesn't work in games based on the content listed previously.

Kayn's ideally meant to get form around 10-15 minutes. However if you're behind and even if you have the wrong runes you should take the first form and try to snowball back into the game. In the "How Kayn Works Section" it describes most of how your match-ups are going to go after form but not before form. Before form you should try to avoid fighting sustain and cc champs like Warwick, Viego. Ganks are key here even if you don't get the kill. If you get form and nobody dies then the gank is worth. If you can almost kill the laners early game don't die to try you'll just feed them, come back after form and it should be an easy kill since you're stronger.

Kayn has a flexible jungle clear the fastest one out of other possibilities is raptors start no matter what side you're on. Red buff with leash can be slightly faster but it's based on what side you spawn and the bot lanes match up, if your bot lane is against a tough comp don't make them leash. Smite buff, and try to early gank immediately for form essence. The full clear should be raptors > drink both potions > red buff > krugs (smite) > wolves > blue buff (smite) > gromp > scuttle crab (smite). The clear can be done without potions but you WILL get low during red buff and will have to instantly smite krugs and be low throughout the rest of the clear. E BETWEEN ALL RED SIDE CAMPS. With a leash you would simply go red buff > krugs (smite) > raptors > and the blue side stays the same. Leashing depends on the match up YOUR BOT LANERS ARE NOT ENTITLED TO LEASH YOU WHEN YOU CAN CLEAR JUNGLE YOURSELF.