Dota 2/Harbringer the Outworld Devourer

Outworld Destroyer is a ranged intelligence hero who is arguably the only intelligence hero that fits the role of a hard carry. He is very reliant on his intelligence stat, from enhancing his spells to weakening enemy casters. He can use Astral Imprisonment to steal intelligence from his enemies. His Arcane Orb and Sanity's Eclipse both become more powerful with more intelligence. He can also buff up his team's spellcasters with his Essence Aura, ensuring that they are almost never starved for mana.

Arcane Orb
Arcane Orb lets you do extra pure damage based on how much mana you have remaining and will do bonus damage to illusions. It is a unique attack modifier and doesn't stack with other unique attack modifiers. It can be auto-cast so that the effect is always applied, but due to its very high mana cost it's best to manually toggle it on and off. It's very weak and completely not worth the mana used when your mana pool is still low, but once you get your intelligence-boosting items and leveled up quite a bit it can do tons of damage. Take note that the damage dealt is pure damage, which will ignore armor and magic resistance.
 * Ability: Auto-Cast, Target Unit
 * Affects: Enemy Heroes
 * Damage Type: Pure
 * Mana Pool To Damage: 6% / 7% / 8% / 9%
 * Illusion Damage: 100 / 200 / 300 / 400
 * Mana Cost: 100

Astral Imprisonment
Astral Imprisonment imprisons an allied or enemy unit, disabling them completely but rendering them invulnerable. If it imprisons an enemy, you will steal their intelligence for one minute. A very annoying harrassing tool during the early stages as well as a way to build up more intelligence. During teamfights, it can be used to take a dangerous enemy out of the battle temporarily or to protect an ally.
 * Ability: Target Unit
 * Intelligence Steal: 2 / 4 / 6 / 8
 * Steal Duration: 60
 * Prison Duration: 1 / 2 / 3 / 4
 * Mana Cost: 120 / 140 / 160 / 180
 * Cooldown: 18 / 16 / 14 / 12

Essence Aura
Essence Aura grants you and allies near you a chance to restore a quarter of your mana pool every time you cast a spell. Abilities that don't have cooldowns as well as toggled abilities will not trigger it. It is very, very useful for heroes that are very mana dependant, you being one of these heroes. When you have a 40% chance of restoring mana at max level, it can feel like your mana will never run out.
 * Ability: Passive, Aura
 * Affects: Allied Heroes
 * Radius: 1000
 * Base Mana: 75 / 150 / 225 / 300
 * Restore Chance: 10% / 20% / 30% / 40%

Sanity's Eclipse
Sanity's Eclipse deals massive damage based on the difference between your intelligence and an enemy hero's. If the intelligence difference doesn't exceed a certain threshold, the affected hero will also lose 75% of their mana. If an enemy hero has the same or higher intelligence than you, Sanity's Eclipse will do nothing to them. This is why you want to get as much intelligence as you can, as you don't want an ultimate that does nothing. The mana drain is also very useful against other intelligence heroes as their intelligence stat will usually be within the threshold required to trigger the drain.
 * Ability: Target Point
 * Damage Type: Magical
 * Radius: 375 / 475 / 575
 * Range: 600 / 650 / 700
 * Difference Damage Multiplier: 8 / 9 / 10
 * Intelligence Threshold: 10 / 30 / 50
 * Scepter Range: 700 / 750 / 800
 * Scepter Difference Damage Multiplier: 9 / 10 / 11
 * Mana Cost: 175 / 250 / 325
 * Cooldown: 160