Dota 2/Huskar the Sacred Warrior

Huskar is a ranged strength hero who is usually played as a carry. He is a favourite among aggresive players due to his high risk high reward playstyle. His Berserker's Blood is what defines Huskar. It makes him stronger the less health he has, letting him turn the tables on enemies thinking that they've found easy prey. Fortunately for Huskar, only one of his abilities use up mana, and the rest sacrifices his health points, bringing him closer to death while greatly damaging his opponents. His Burning Spears do stackable damage over time, letting Huskar rack up a lot of damage. His Inner Vitality consumes mana, but it is a healing spell that becomes more powerful the less health the target has, in case Huskar finds his health to be too low for comfort. Finally, he has Life Break, which uses up a portion of his health to take away an even bigger chunk of health from his enemy, initiating duels with foes that they cannot win.

Inner Vitality
Inner Vitality heals the targeted ally over time for sixty seconds based on their primary attribute. The healing is increased if the unit has less than 40% health remaining. It is the only ability that costs mana, but it fits in quite well with your other abilities, as it lets you heal yourself back up after draining your own health for more power. It is also a good support ability to keep your teammates alive, though since you are usually a carry you wouldn't be using it for that purpose too often.
 * Ability: Target Unit
 * Affects: Allied Heroes
 * HP Regen: 2 / 4 / 6 / 8
 * Bonus From Attribute: 5% / 10% / 15% / 20%
 * Bonus When Hurt: 30% / 45% / 60% / 75%
 * Mana Cost: 170
 * Cooldown: 25

Burning Spears
Burning Spears is a toggled ability that makes your attacks ignite the enemy for 7 seconds, dealing additional damage over time, though each attack uses up a bit of your health. You cannot kill yourself with this ability. It is a Unique Attack Modifier and doesn't stack with other Unique Attack Modifiers. It can be auto-cast to apply its effects on every attack provided that you have enough health, though this is not recommended as your health will drain away rather quickly. The great thing about this ability is that it is fully stackable with itself, dealing more damage if the previous instance isn't done. The health drain is also a good way to bring your health down and make yourself more powerful, though if you are already under fire it might be best not to activate it.
 * Ability: Auto Cast, Target Unit
 * Affects: Enemy Heroes
 * Damage Type: Magical
 * Damage: 5 / 10 / 15 / 20
 * Health Cost: 15

Berserker's Blood
Berserker's Blood gives you bonus attack speed and magic resistance for every 7% of health you lost. That means you can get a maximum of 280 attack speed and 98% magic resistance at 2% health on level 4, though you will rarely ever be fighting with so little health. Still, your damage output increases exponentially once your health drops below half, so enemies seeking an easy kill may find that they are the ones that are getting killed. The increased magic resistance also prevents you from getting killed by high burst damage.
 * Ability: Passive
 * Bonus Attack Speed: 8 / 12 / 16 / 20
 * Bonus Magic Resistance: 4% / 5% / 6% / 7%

Life Break
Life Break makes you leap at the target, taking away a chunk of their current hp while sacrificing some of yours, while slowing them for 5 seconds. During the leap you are magic immune. It can be a deadly way to initiate a kill, halving the health of your target and making it difficult for them to escape. The health loss you take also helps you increase the Berserker's Blood buff, making you even more lethal as you wear them down.
 * Ability: Target Unit
 * Affects: Enemy Heroes
 * Damage Type: Magical
 * Slow: 50%
 * Damage Taken: 40% / 35% / 30%
 * Damage Dealt: 50%
 * Cooldown: 45 / 30 / 15
 * Scepter Damage Dealt: 65%
 * Scepter Cooldown: 4

Aghanim's Scepter can be bought by Huskar and will increase the damage dealt by Life Break and will greatly decrease its cooldown.