Zul'Jin (kit section added) by Chatpelier

Level 1 :

[Long Throw] - Q : Axes now travel double the distance (8-shape).

[Quick Throw] - Q : Reduce Double Axe Throw cooldown by 2 seconds.

[Pyromania] - E : Increase fire radius by 33% and duration by 2 seconds.

[Regeneration Master] : Collecting Regeneration Globes permanently increases Health Regeneration by 1.5 per second.

Level 4 :

[Troll Metabolism] - Trait : While at full health, Zul'Jin health regeneration grants him a shield up to 10% (+0.5% per level) of his maximum health.

[Axerang] - Q : Axes now come back to Zul'Jin, dealing 60% damage on the way back.

[Acid Concoction] - E : Unstable Concoction now deals triple damage to structures.

[Envenom] : Activate to poison an enemy Hero, dealing 209.88 (+29.92 per level) damage over 10 seconds.

[Amplified Healing] : Increases regeneration effects and all healing received by 30%.

Level 7 :

[Poisoned Net] - W : Amani's Net now deals 115 (+15 per level) damage over 5 seconds to enemies trapped in it.

[Spark Off] - E : Unstable Concoction fire destroy 2 Ammunition per second, making them explode, and dealing 26 (+4.5 per level) damage in a small area.

[Intriguing Fire] - E : Unstable Concoction fire now reduces the duration of silences, stuns, slows, and roots against allies by 33%.

[Mercenary Lord] : Non-Boss Mercenaries near your hero deal 50% more damage. Reduces damage taken from Minions and Mercenaries by 50%.

Level 10 :

[Troll Berserker]

[Grievous Throw]

Level 13 :

[Oiled Axe] - Q : Using Double Axe Throw over Unstable Concoction fire ablaze the axes, dealing 30 (+24 per level) damage per second over 4 seconds to enemy hit.

[Big Net] - W : Amani's Net is now thrown in a small area (~Nazeebo Wall of Zombies).

[Oiled Net] - W : Amani's Net is soaked in oil. Enemies soaked in oil take 100% more damage from Unstable Concoction.

[Giant Killer] : Basic Attacks against enemy Heroes deal bonus damage equal to 1.5% of the Hero's maximum Health.

Level 16 :

[Triple Axe Throw] - Q : Now throw 3 axes (the third one right in front of him). Stun duration increased by 0.5 seconds.

[Heavy Net] - W : Amani's Net now also slows targets by 30% for 3 seconds once the root effect fades.

[Instant Regeneration] - Trait : Upon taking fatal damage, instantly regain 25% of your maximum Health, but deactivate Regeneration for 10 seconds. This ability has a 90 second cooldown.

[Blood for Blood] : Activate to deal 10% of target enemy Hero's Max Health and heal for twice that amount.

Level 20 :

[Quick Regeneration] - R1 : You can now press R to loose the 15% damage increase, double health gain through Regeneration and increase your movement speed by 20% for 6 seconds. This ability has a 40 seconds cooldown.

[Master Thrower] - R2 : Zul'Jin can move freely while channeling.

[Nexus Frenzy] : Increases Attack Speed by 20% and Attack Range by 20%.

[Bolt of the Storm] : Activate to teleport to a nearby location.

Now that you've got an idea of what he's capable of, let's look at his kit for a sec.

(Trait) Regeneration is pretty straightforward since it works like Muradin's passive, but is still active in combat. Zul'Jin is really squishy, has less health than most of the other champs, but his passive makes up for that. The less health he has, the faster he regenerated. That means that if he's not burst quickly, he can keep fighting for a very long time. Remember that he's not using mana either. In that way he's like Raynor or Illidan, he shines when the fight tends to go on for a lot of time.
A few talents can give you a bit more survivability if you're facing Zeratul, Nova and other bursty heroes that'd wreck you otherwise.

(Q) Double Axe Throw is the typical bread and butter spell : it deals damage, and if landed well, stuns targets. Axes will cross trajectory just in front of you, and when the loop ends, if you take Long Throw, they cross a third time, and if you take Axerang, they'll cross 2 more times on the way back. It's not easy to land, but it can do miracles, and do a lot of area damage, especially if you add Triple Axe Throw to the lot.
Of course, you could also take Oiled Axed to ablaze your axes in order to burn your targets.

(W) Amani's Net allows you to avoid dying from ganks (if you're lucky), catch a fleeing target or win a duel against another ranged (auto attacking) hero like Valla or Raynor. Rooting and slowing attack speed won't necessarily help you against magic casters though, for that, you'll need to land your Q and outburst your target.
If you find that landing your W is really easy and wins you a lot of fights, you could always take Big Net to root more enemies, or go for more damage with Poisoned and/or Oiled Net.

(E) Unstable Concoction is what makes you a good pusher aswell. You're not the best at it, but you're still a threat when you get the opportunity to sit under a tower for a few seconds. It's also a great way to reveal stealthed heroes, and has good synergy with your other two basic abilities if you take the right talents : Oiled Axe or Oiled Net for example. A good way to burst would be W>E>Q (+Envenom) with either of those talents.

(R1) Troll Berserker is "just" a passive that makes you way scarier than you already were, but also makes you even squishier than you already were. Don't worry, at level 20, you'll be able to get an active skill out of this, but before that, to position yourself and land all those skillshots is the key of you winning the fights.
Quick Regeneration is a way for you to be safer AND catch your opponents. Kite them and kill them when they flee.

(R2) Grievous Throw is similar to Diablo's Lightning Breath, but is redirected with R instead, allowing you to move freely after taking Master Thrower at level 20.
You'll be able to deal a lot of damage if you position yourself in the right place, and will also slow the entire area, allowing your teammates to easily catch up with the other team.
It's a tool that fits well with other AOE ultimates, like Phoenix, Mosh Pit or Starfall, for exemple.