Dota 2/Slark the Nightcrawler

Slark is a melee agility hero who is usually played as a ganker or a carry. His abilities make him a great assassin, taking down individual heroes and slipping away after the deed is done. Although his agility, his primary attribute, is lower than his other attributes, he can potentially get a heap of agility with Essence Shift, weakening his enemies at the same time. His Dark Pact is a handy nuke that also purges debuffs, letting him escape disables by sacrificing a bit of his life. His Pounce can be used as an escape mechanism, but it can also be used to leash opponents, leaving them vulnerable to your attacks. His ultimate, Shadow Dance, is an odd invisibility ability that makes him untargetable but still leaves him visible in the form of an ominous black cloud, making him free to pound on his enemies without them able to attack back. It also makes him much more survivable once he escapes his enemy's sights. Slark is a hero that can get a kill fast and slip away, spreading terror among his foes when they see him cloaked with dark fog.

Dark Pact
Dark Pact sends out a dark pulse of energy after a short delay, purging all negative debuffs and dealing damage to enemies around you and half the damage to yourself. You cannot die from the self-damage. It is a simple nuke for dealing damage, but the self-damage might not make it very desirable if your goal is just to damage your foe. The purge effect is quire useful though, as you can use it to remove any disables or harmful effects from you with a relatively low tradeoff. You can also use it to dodge certain debuff spells, such as if you see a ranged disable like an Ensnare or a Shackleshot flying towards you, casting Dark Pact just before it hits will remove its effects immediately. It has a short cooldown, which makes it a spammable damage spell during teamfights.
 * Ability: No Target
 * Damage Type: Magical
 * Delay: 1.5
 * Radius: 325
 * Damage: 75 / 150 / 225 / 300
 * Mana Cost: 55 / 50 / 45 / 40
 * Cooldown: 9 / 8 / 7 / 6

Pounce
Pounce makes you leap at the direction you're currently facing. You will damage the first enemy hero you collide with as well as leash it, which prevents it from moving too far from the leash point. It serves as an effective escape mechanism, though it can be very useful for chasing enemies too, especially if you manage to leash a hero. Aiming for the hero you want to leash can be a bit tricky, since you must be facing that hero and not just target it directly like most target unit or target point spells. If you can get a leash off, you can get a few attacks on that enemy, potentially getting the kill. It's cooldown is reduced enough by level 4 that it can be spammed.
 * Ability: No Target
 * Damage Type: Magical
 * Distance: 700
 * Pounce Damage: 60 / 120 / 180 / 240
 * Leash Duration: 3.5
 * Leash Radius: 325
 * Mana Cost: 75
 * Cooldown: 20 / 16 / 12 / 8

Essence Shift
Essence Shift lets you steal 1 point of each attribute from your target and grants you 3 bonus agility with every attack. You can weaken a hero severely with several attacks, while getting more powerful yourself. More agility means you get more damage, more armor and more attack speed. It also means that you will do more damage with each consecutive attack on the same hero. Even if you didn't kill your target, the effect lasts for a long time, especially by level 4, so the attacked hero will be a lot weaker and you will be a lot stronger for a minute or two.
 * Ability: Passive
 * Agility Gained: 3
 * All Attribute Loss: 1
 * Duration: 15 / 30 / 60 / 120
 * Cooldown: 0.4 / 0.35 / 0.3 / 0.25

Shadow Dance
Shadow Dance surrounds you in a shadowy fog, turning you invisible. Enemies can still see the dark fog, but they won't be able to attack you or cast target unit spells on you, or even remove your invisibility with true sight. You can still cast spells and attack without breaking your invisibility. It also gives you a passive effect where you will get increased health regeneration and movement speed as long as you're not visible by the enemy. The active spell effectively gives you partial invulnerability, but you're still vulnerable to AoE attacks. It still ensures that the enemy has limited ways to fight back when you're in the fog. The passive ability means that you have a much better chance of surviving once you're away from enemy vision.
 * Ability: No Target
 * Duration: 4
 * Bonus Movement Speed: 30% / 35% / 40%
 * Health Gained Per Second: 3% / 5% / 7%
 * Mana Cost: 120
 * Cooldown: 60