Lina

Lina the Slayer is a ranged Intelligence hero, adept at destroying enemy heroes quickly by delivering massive bursts of magical damage, making her one of the most effective gankers in the game. She possesses immense damaging capabilities all throughout the game, but is very fragile. Two of her fiery spells are her main source of damage, Dragon Slave sends a wave of fire to burn enemies in her path while Light Strike Array stuns them with a concentrated pillar of solar flame. Each of her spells deals great damage early on and has a low cooldown. Her Fiery Soul bolsters her attack and movement speed every time she casts a spell, which gives her scaling damage for the later game. Laguna Blade, her ultimate, is her ace in the hole. Lina fires off a huge bolt of lightning at a single target, dealing colossal damage. Laguna Blade's damage is staggering in early-mid game, and late game is still enough to destroy frail enemy heroes. Dragon Slave, Light Strike Array, and Laguna Blade are incredible flaming nukes that can incinerate her target instantly, and Fiery Soul allows her to transition into a strong and fast physical attacker. Though her power falls from its peak late game, mana-boosting and damage-increasing items can be purchased to keep herself up.

Tips

 * Combining Light Strike Array with a guaranteed stun such as Vengeful Spirit's Magic Missile or Sven's Storm Hammer makes Lina a serious ganking force early on.
 * Positional items such as Eul's Scepter of Divinity, Blink Dagger, Force Staff or Phase Boots can help you a lot landing Light Strike Array and thus your whole spell combo without relying on other heroes.
 * Always cancel the backswing animation after casting your spells, as Lina suffers from long animation times.
 * In teamfights it can be very beneficial to quickly focus on low-HP or support heroes, as Lina has very good nuking abilities.
 * When paired with Pugna or Shadow Demon, both of whom have percentage-based damage-increasing mechanics; Lina's burst damage becomes gigantic (a sceptred level 3 Laguna Blade will do about one thousand damage alone) to the extent where she can assassinate enemy heroes with a significant gear/level advantage over her.
 * If Lina has the basic items she needs, it is wise to augment her physical attack for the sake of Fiery Soul. Almost uniquely among Intelligence supports, Lina's rightclick becomes a serious threat if she attains a level advantage (owing to her enormous Int growth and her passive ability). Some basic items for this build are Daedalus, Eye of Skadi and Monkey King Bar, as well as some form of lifesteal.
 * Dagon can be used to nearly double the burst damage of Lina's ultimate.
 * Lina's Laguna Blade can hit for 1900 damage if she combines Aghanim's Scepter and, granting her enormous nuking power.
 * While unmentioned purchasing an Ethereal Blade if the farm is available combined with an Aghanim's Scepter and Lina's naturally high Intelligence gain will give you a perfect combination of survivability through stats, armor and Ghost form and an enormous increase in damage output allowing Lina to instantly kill most low to average HP heroes provided that she lands all of her spells during the Ether Blast. The slow provided by Ether Blast also comes in very handy in landing Light Strike Array (The damage from an Aghanim's Scepter upgraded Laguna Blade is not amplified by the Ghost Form, since it is pure damage).
 * If Lina is tending to be targeted first (this is a very common tendency), some survival-increasing / utility items will be of great use.
 * Some players advocate building a Dagon in place of an Aghanim's Scepter, as it is cheaper (though not if upgraded) and ultimately does more damage (through both its active and its bonus to her attack damage). However, Aghs makes her significantly more durable, whereas Dagon does only slightly, and Lina is very fragile. If you think you are unlikely to die very much, Dagon is probably the wisest choice. However, Aghs can be a wise choice if there are some bkb's in the game or if playing against a Lifestealer or a Juggernaut as they both have magic imunity spells.
 * For Fiery Soul to take to its peak, cast Dragon Slave, Light Strike Array, and Laguna Blade successively to take the speed-enhancing effect of Fiery Soul to its maximum potential.
 * Though somewhat difficult as Lina's survivability is very low, it's possible to play her as a carry due to the fact that she can greatly increase her DPS for 10 seconds simply by casting spells, and both of her first two spells have shorter cooldowns than 10 seconds, meaning the player could potentially be permenantly under a high attack speed increase during teamfights and pushes. If this path is chosen, items such as an Eye of Skadi are extremely effective on her as she becomes much more survivable and gains potent right clicks.

Trivia

 * The original Lina Inverse "The Slayer" was modeled after the main character from the novels/anime/manga Slayers where, and  are all spells used by the original Lina Inverse.
 * Lina's line lina death 10.mp3 "Better to burn out than fade away" is a reference to the Neil Young song, My, My, Hey, Hey.
 * The line also appears in the suicide note of Kurt Cobain.
 * The line lina death 09.mp3 "Turn me over... I'm done." is a reference to Lawrence of Rome who was roasted alive on a giant grill and joked, "Turn me over — I'm done on this side."
 * In Dota 2 Lina and are sisters with a bitter rivalry and have many unique responses when they encounter or kill each other. In Warcraft DotA, however, they are unrelated as evidenced by lack of mentions in each other's lore and their apparent different surnames (Inverse and Crestfall, respectively).
 * Lina's rival response towards Lina rival 19.mp3 "Why'd you stop? This isn't Batrider country." is a reference to a line in the movie Fear and Loathing in Las Vegas.
 * In older versions of DotA, Lina was a male hero that used the Blood Mage model, also used by the Invoker. In these versions, Lina was known as Link Inverse.
 * Lina's line Lina kill 08.mp3 "It's not the heat, it's the humiliation." is a reference to "It's not the heat, it's the humidity." used in tropical countries where humid weather causes people to sweat heavily although the temperature is not very warm.