Riki

Riki the Stealth Assassin is a melee agility hero that uses stealth in order to surprise enemies and quickly kill them. His trademark ability, Permanent Invisibility, allows him to sneak into the shadows to hide and slip by without giving himself away. This allows him to close in on the enemy and drop his devastating Smoke Screen, which cripples fighter and spellcaster alike. Blink Strike allows Riki to chase with impunity, and Backstab makes running from him even more dangerous.

Gameplay
Riki's invisibility is both his greatest strength and his greatest weakness. On one hand, it makes him able to surprise enemies and farm with very little concern. On the other hand, without invisibility he has no real defense. He still has to watch out for revealing items such as Dust of Appearance and Gem of True Sight, as well as abilities that prevent him from going invisible. If he stays alive and picks off lone enemies, he can quickly get out of control.

Smoke Screen provides a powerful Silence and gives enemies a high miss chance, as well as slowing them down. If targeted properly, it can hold an enemy down long enough to finish them off. However, enemies must stay in the area to be affected. A good strategy is to throw a Smoke Screen in the enemy's path, rather than where they are presently. Blink Strike is Riki's chase and escape ability. It operates like other Blink abilities, in that it allows Riki to teleport to a target quickly. However, Blink Strike must target a unit. It helps catch up with fleeing enemies, jump into fights quickly, and escape from situations by targeting allies. Blink Strike pairs well with Backstab, because it teleports Riki behind the enemy. Backstab causes any attack from behind to deal additional damage, and allows you to absolutely flatten weaker enemies. If they turn to run, Riki suddenly hits for much more. Finally, Riki's Permanent Invisibility allows him to go completely invisible after a short delay. If Riki's enemies don't have any form of detection, this lets Riki escape with ease and roam freely. If they do, Riki has to rely on his cunning and speed in order to get the drop on enemies, and get out alive.

Tips

 * Don't walk straight up to enemies and deep into enemy territory and expect never to die. If they have any kind of detection(e.g. sentry wards), then Riki dies very fast.
 * As a result of this, make a habit of constantly checking the enemy's inventory for revealing items.
 * His trademark skill Permanent Invisibility is the key that allows to be one of the best support killers in the game,since good supports will always stay behind you can flank the enemy team coming around from there and catching the supports as soon as the teamfights begin,the enemy team will be so busy fighting yours that will not realize that their supports are already dead. This strategy also applies to enemy initiators with gamebreaking ultimates like  or  a good interruption as this can set victory in critical situations.
 * Riki is exceptional at ganking lone heroes and picking them off one by one. He can snowball easily through just getting lots of kills even without farm. Try to get kills before the enemy starts grouping up however, because Riki falls off late-game as enemies purchase detection items.
 * Blink Strike can target allies and enemies. Jumping to a friendly unit can be useful in case Riki needs to escape, also you can target the enemy courier, allowing for an easy kill.
 * Heart of Tarrasque can be a good item for Riki; his Permanent Invisibility allows him to slip away and let the passive regenerate him without fear of interruption.
 * An early Orb of Venom will give Riki a good slow that may help with early kills. Remember that since 6.83 patch Diffusal Blade is no longer UAM so it will stack with other ones.
 * Only upgrade the Diffusal Blade when it's out of charges, as you buy the Diffusal Blade for the active primarily. This will allow for more kill potential as well as more escape (in that you can purge debuffs).
 * Manta Style gives good stats and allows Riki to remove debuffs such as Dust of Appearance without using Diffusal Blade charges.
 * Due to the nature of Permanent Invisibility, a well-organised team may be efficient with buying Sentry Wards to keep vision of you. You may want to take it upon yourself to 'de-ward' your lane if needs be; if you're without a support, or so that your support can concentrate on other items.
 * Save the early Orb of Venom and once the game reaches later stages you can upgrade to Eye of Skadi for one more reliable slow that penetrates BKB.
 * You can take Permanent Invisibility as your first skill point and easily take the first Bounty Rune in either of top or bot sides of the river,so the enemy won't have any forms to detect you.
 * is a key hero to catch slippery foes and heroes that are heavily reliant on their own active skills since he can approach without detection and use smoke to prevent them from using escape spells,so its wise to pick him as a counter pick to many heroes like ,,,,, however, be careful of enemies carrying escape items,like Force Staff or Shadow Blade.
 * Be wary around more durable enemy heroes. Spell Immunity from  allows enemies to ignore  and fight Riki, removing his Backstab advantage.
 * Always scout the enemy jungle once in a while,you may encounter some enemy farming alone for a easy kill, also help high mobility heroes like or  to set up a gank.
 * Don't be afraid of enemies carrying Gem of True Sight,track down their movement and wait, sooner or later they're going to end up alone and when this happen don't hesitate, use the fog of war and approach form the sides, go for the kill and recover the Gem.

Trivia

 * In DotA, Riki was called "Rikimaru"; Rikimaru is also the name of a main character in the Tenchu game series.
 * Riki's fun/alternate name was Riki Martin, which is a pun on Ricky Martin, a famous Latino pop singer.
 * Riki's line upon dying, riki death 09.mp3 "Good assassins never die… they just fade away.'" is a reference to the General Douglas MacArthur quote, "Old soldiers never die; they just fade away."
 * Riki's line Riki kill 10.mp3 "There are none so stabbed as those who will not see." is a reference to "A christmas Carol" where a blind woman says, "I am not so blind as those who will not see.".
 * Riki's line Riki spawn 08.mp3 "I speak softly, but carry a sharp knife." is likely a reference to the West African Proverb "Speak softly and carry a big stick.", popularized by U.S. president Theodore Roosevelt.
 * Riki has the highest base stat of any hero.
 * In the early versions of DotA, 's was actually Riki's ultimate ability which did not require any channeling and allowed him to place the ward anywhere to attack enemies. Riki's skill set also included a regular blink ability and a critical strike instead of the current  and.