Dota 2/Riki the Stealth Assassin

Riki is a melee agility carry hero who is known for being very elusive. He can stay invisiable forever with his Permanent Invisibility, stalking his enemies without them even knowing. His Smoke Screen helps him evade attacks as well as disabling enemies, while his Blink Strike is excellent for chasing or escaping.

Smoke Screen
Smoke Screen makes a lingering puff of smoke appear in the target area, silencing, slowing as well as causing enemy attacks in the smoke screen to miss. A helpful disable to let you escape enemies or catch up to them. Remember that since enemies can only be affected by the Smoke Screen if they stand in it, you should put them in the direction of where they will be instead of where they are, for a better chance of catching them longer.
 * Ability: Target Point
 * Radius: 250 / 275 / 300 / 325
 * Miss Rate: 40% / 50% / 60% / 70%
 * Slow: 25%
 * Mana Cost: 75 / 80 / 85 / 90
 * Cooldown: 13

Blink Strike
Blink Strike makes you blink behind the target unit, striking it for bonus damage if it's an enemy. It increases your mobility, but only if there are units that you can blink to. You can use it to catch up to an enemy, placing you conveniently in the position to activate your backstab, or to escape by blinking to a nearby ally.
 * Ability: Target Unit
 * Damage Type: Magical
 * Damage: 30 / 60 / 90 / 120
 * Range: 700
 * Mana Cost: 50
 * Cooldown: 20 / 15 / 10 / 5

Backstab
Backstab will let you do a bonus amount of damage depending on your agility stat provided that you attack your opponent from behind. With your invisibility and Blink Strike, it should be quite easy to get behind an opponent for a backstab. If your target is fleeing, it actually makes them more suscaptible to backstabs since their backs will be facing you.
 * Ability: Passive
 * Damage Type: Physical
 * Agi Damage Mult: 0.5 / 0.75 / 1 / 1.25

Permanent Invisibility
Permanent Invisibility, as the name suggests, lets you stay invisible permanently, only dropping it temporarily when attacking or using an ability. This is why Riki is so deadly. You can easily appear from nowhere and take an enemy by surprise. Be careful that you don't get silenced, since you will lose your invisibility for the entire duration of the silence.
 * Ability: Passive
 * Fade Delay: 3 / 2.25 / 1.5