Rek'Sai
Needs a nerf.
Passive shouldn't proc on minions. Makes her too potent a laner who doesn't really have to trade to get free healing. Furious Bite should cost her fury bar. There is absolutely no reason for her to deal 240% of her AD as TRUE DAMAGE with no cost. Makes it impossible to split against her. Ultimate cooldown needs to be wayyyy over 150/110/80. Easily 250/225/200. She has way too much map pressure and it's impossible to break enough of her tunnels to limit her ultimate unless you're completely dominating her.
Riot you need to seriously learn that you can't make fluid role junglers. They can't lane. You have to make it literally impossible for them to lane. Since I started playing in season 2 I have not once experienced a jungler who is both balanced in lane and in the jungle.
Another huge mistake you make is giving these champions like Rek'Sai a retarded amount of utility (Can literally dash across the entire map with proper tunnel placement), and then giving them the ability to still do retarded amounts of damage on their remaining abilities. There's also the question of why Rek'Sai can complete her ultimate to a tunnel that's being destroyed. If she's already moving toward it sure, but she should cancel her ultimate if the tunnel gets destroyed before she starts to dash toward the tunnel.
And on top of that quit giving these champions random fucking passives. Why in the hell does Rek'Sai have free attack speed on her ultimate? She's not a carry, why give her attack speed? Force her to build it if she wants to go carry. But oh wait her fucking attack speed doesn't matter, all she wants to do is Furious Bite everyone for half their HP anyway.
You don't give a jungle good scaling. That just makes them a laner. You give them good bases and lower scaling. They simply can't be allowed to lane because their kits are extremely toxic to lane against. Look at Lee fucking Sin for example. Free attack speed, free trading with Q>W and a shield to go with it.
This is somewhat a rage rant, but seriously riot what were you thinking? The Jungle was hard and someone needed 10 training wheels to even clear it?