Warbringer by devonitar

Source of inspiration for this hero comes far from the StarCraft: Brood War era. Reaver was then a protoss artillery unit, unique for having to create its "ammunition", scarabs. Its damage (100 or 125 when upgraded) was the most devastating single attack in the multiplayer, and this is without counting any potential splash damage. However, its infamous speed (another extreeme: slowest unit in the game) and friendly fire possibility led to its initial low use. Still, some high-level players managed to get pass Reaver's downsides by pairing it with another protoss unit, the Shuttle. Shuttle transported Reaver around, enabling it to deal massive damage to the enemy's worker line or practically any ground units and buildings. It required great skill of micromanaging, and ever since release of StarCraft II, the playerbase expressed their sentiment towards the robotic caterpillar-thingy. This concept is meant to show, that they are some old skill-based Blizzard mechanics that can be revived for the use in Heroes of the Storm.

Examples of Reaver gameplay are bellow:
Play Video Play Video
Warbringer itself is a canon individual. It is a Protoss Reaver hero unit in the StarCraft Map Editor and can be played in the official and additional campaign of StarCraft: Enslavers. Starchaser is a "made-up" character to represet Protoss Shuttle in this duo.

Based on this concept, Warbringer+Starchaser duo is a specialist hero, specialized in critical attacks, split pushing and threat shift during teamfights. Warbringer deals massive damage, which is somehow limited by scarab pathing (it can pass through minions, heroes and mercenaries, but buildings and terrain obstacles cannot be passed) and requirement of macromanaging a resource of Psionic Power, which is necessary for creating additional scarabs, but also for any other basic ability the duo posseses. This is limiting, but can be worked through some talents. Micomanaging Warbringer and Starchaser is required to properly position the Reaver and save it from dangers. I imagine (though I have no idea how the HotS engine works those things out) that loading Warbringer into Starchaser would render projectiles fired at the Reaver harmless, just like in StarCraft. Player has to manage two heroes, each supplementing each other, and death of any of them can result in death of both. Obviously, this hero would be labeled as Very Hard.

Warbringer:

Health: 550 (+100 per level)
Health Regen: 1.50 (+0.30 per level)
Mana: 0
Health Regen: 0
Attack per second: 0.80
Attack range: 9.00
Damage: 140 (+20 per level)
Movement speed: 0.30

Starchaser:

Health: 500 (+90 per level)
Health Regen: 1.50 (+0.30 per level)
Mana: 0
Health Regen: 0
Attack per second: 0
Attack range: 0
Damage: 0
Movement speed: 1.2

Storage Capabilities (Warbringer - Q)
- Increases maximum scarabs that can be hold at the same time by 2.
Rollout (Warbringer - Passive)
- Each second of regular movement increases movement speed by 10%. Stacks up to three times. Stopping for one second restores original speed.
Extra Plated Hull (Starchaser - Passive)
- Increases health points by 10%.
Evac (Starchaser - Q)
- Loading Warbringer increases movement speed of Starchaser by 20% for 2 seconds.

Extrapolation (Warbringer - Trait)
- Increases basic attack range by 10%.
Active Shields (Starchaser - Trait)
- Starchaser now constantly regenerates shields, regardless of the damage taken.
Psionic Absorbtion (Trait)
- Takedowns regenerate 2 Psionic Power.
Engineering Bay (Warbringer - Q)
- Scarabs requires 0.5 second less to create.

Repairing Nanobots (Starchaser - Q)
- When ferrying, Warbringer is restoring 2% health each 2 seconds.
Targeting Beacon (Starchaser - W)
- Enemies damaged by Sonicboom take increased scarab damage by 20% for 3 seconds.
Sensor Array (Starchaser - Passive)
- Increases sight range of Starchaser by 25%.
Psionic Projection (Warbringer - W)
- Plasma Illusion requires 2 less Psionic Power when used aboard Starchaser.

Obliteration Beam (Warbringer - R)
- Warbringer channels a fiery beam at the selected hostile target, dealing 42 (+2 per level) damage every second. Lasts 5 seconds. Basic attacks and moving can be performed normally. Ferring Warbinger or using any of its ability cancels the effect.

Dematerize (Starchaser - R)
- Starchaser turns invisible and immune for 3 seconds.

Khaydarin Power Source (Trait)
- Use to instantly restore 5 Psionic Power. Cooldown is 45 seconds.
Warp Reinforcements (Passive)
- Whenever one of your machines remain alive, the other one has 50% reduced respawn time.
Unleashed Psi (Warbringer - W)
- Restores 2 Psionic Power when the Illusion damages enemy hero upon reaching its final destination.
Void Prism (Starchaser - Q)
- Starchaser can now use Ferry from the distance.

Burning Plate (Warbringer - Passive)
- Warbringer constantly deals 12 (+2 per level) damage each second to every enemy around.

Scarab Reserves (Warbringer - Q)
- If no scarabs remain, Create Scarab costs no Psionic Power.

Plasma Matrix (Starchaser - Passive)
- Whenever Warbringer remains under Starchaser, it restores 55 (+10 per level) shields per second, up to amount of 50% of Warbringer's total health.
Nebula (Starchaser - W)
- Increases damage done by Sonicboom by 15 (+5 per level) for each enemy targeted.

Colossus Ray (Obliteration Beam (R))
- Increases damage done by Obliteration Beam by 25%. Additionally, it deals 50% of regular damage to nearby hostile targets.
Hallutinations (Dematerize (R))
- Dematerize's cooldown is reduced by 10 seconds. Additionally, now summons a copy of Starchaser and Warbringer that begin to simulate their typical actions. Copies deal no damage.
Nexus Starcharts (Starchaser - Trait)
- Starchaser can now fly over terrain obstacles.
Protectorate Artillery (Warbringer - Trait)
- Scarab damage chains now up to three nearby enemies (prioritizing heroes), dealing 30% of normal scarab damage.

http://starcraft.wikia.com/wiki/Reaver
http://starcraft.wikia.com/wiki/Reaver_%28StarCraft%29
http://starcraft.wikia.com/wiki/Shuttle
http://starcraft.wikia.com/wiki/Warbringer
http://starcraft.wikia.com/wiki/StarCraft:_Enslavers
http://wiki.teamliquid.net/starcraft/Reaver
http://wiki.teamliquid.net/starcraft/Shuttle

22.06 - Changed aesthetics and some descriptions in the Talent section; changed Protoss Reaver trait; added "Movement speed" in the Statistics section.