Herald Volazj by MagicPants

Tier 1:

Flay All Minds: Quest: Mind Flay 70 times. Reward: Mind Flay now lasts 5 seconds and every use will permanently increase it's damage by 1%.

Shadow Crash: Quest: Hit 20 Heroes with Void Bolt. Reward: Void Bolt will now knock the target away and leave behind a pool of void energy that deals 75 (+4%) damage every second and reduces enemy healing received by 50%. The pool lasts 3 seconds.

Eldritch Horror: Quest: Spread Shiver 80 times. Reward: Shiver's duration is increased by 3 seconds and it's damage is increased by 10%.

Tier 2:

Stunned by Madness: Quest: Hit 20 enemy heroes with basic attacks. Reward: Every basic attack against enemy heroes, non-boss mercenaries and minions will stun the target for 0.25 seconds.

Void Bringer: Reduce the cooldown of Void Bolt by 5 seconds.

Shivering Presence: Taking melee damage will automatically apply Shiver to the attacker.

Psychic Backlash: Being stunned or put to sleep will increase the range and damage of Mind Flayer's Presence by 100% for 6 seconds. This effect can stack.

Tier 3:

Dark Gift: Activate to give 50% of your current mana to the target allied hero. Cooldown: 30 seconds.

Soothing Pain: Activate to increase an allied hero's healing received by 50% for 5 seconds. Cannot be used on Volazj. Cooldown: 30 seconds.

Whisper of Despair: Activate to reduce the target enemy hero's damage by 40% for 5 seconds. Cooldown: 30 seconds.

Exuding Evil: Increase the range of Mindflayer's Presence by 50% and it will heal you for 50% of the damage dealt.

Tier 4:

Doom

Deep Corruption

Tier 5:

Dream Eater: Mind Flay will deal 50% additional damage when cast on a sleeping target and heal Volazj for 100% of the damage inflicted. If the target is awoken during Mind Flay, this bonus damage and healing is lost.

Void Flash: Activate to teleport a short distance. Cooldown: 30 seconds.

Spell Shield: Every 30 seconds, gain 50 Spell Armor against the next enemy Ability and subsequent Abilities for 3 seconds, reducing the damage taken by 50%.

Tier 6:

Cerebral Ravage: If an enemy hero activates a basic ability or heroic while under the effects of Mind Flay, it is refreshed and deals 50% more damage. This effect cannot stack.

Void Thrashing: If Void Bolt kills an enemy hero, the hero explodes dealing 250 (+4%) damage to all nearby targets and its cooldown is reduced by 10 seconds.

Psychic Explosion: When Volazj dies, after 0.25 seconds he deals 800 (+4%) damage to all enemies in melee range.

Aura of Insanity: Mind Flayer's Presence deals 55% less damage but it's damage ticks every 0.25 seconds.

Tier 7:

Pandemonium: If a target dies 5 seconds after casting Doom on them, it will fear their nearby allies causing them to flee in terror for 2 seconds and Doom's cooldown will be reduced by 50 seconds.

Volatile Corruption: Enemy heals will no longer end the curse and the curse will end with a final detonation whether the target was healed or not.

Insanity: Activate to make a shade of the target enemy hero that has 50% of their max health and deals 30% of their damage. The shade will only attack the copied hero and will continue to pursue them. Lasts until killed. Cooldown: 40 Seconds.

Touch of the Mind Flayer: Basic attacks refresh Mind Flay and Shiver on the target.

Mind Link: An untalented Mind Flayer's Presence can now be activated and applied to an allied hero causing them to deal 30 (+4%) damage to nearby enemies every second for 5 seconds. Cooldown: 15 seconds.

The idea behind this character was to give the Faceless Ones a place in HOTS. I designed him with a capable amount of poke damage, but with his real strength being in dealing high damage to nearby enemies. This would make him stronger against dive heroes and give him considerable wave clearing ability. However, he has no real means of escape or hard engage until level 13 through Void Flash. This would make him vulnerable to heroes that can deal high ranged damage and heroes that can dash in and out quickly before he has time to react.
In effect, this makes him a character that can zone enemy heroes away with his body rather than his skills. Both Mind Flay and Shiver would have short range, with Void Bolt being his only ranged ability. His trait is basically the same as other aura based damage abilities but with increased damage and range since he is an assassin and not a warrior. The range on his trait would be about equal to Li Ming's teleport after her range upgrade. This would fulfil his role as an anti-melee hero while also limiting his ability to effectively harm ranged enemies.
I personally feel it would be great to have a Faceless One in HOTS and Volazj in my opinion is a classic villain from WOW.

He is designed to punish melee heroes and therefore is great vs sticky heroes, but he is weak against range poke making heroes such as Zul'Jin a nightmare.

Strong Against: Illidan, Valeera, TLV, Murky, D'va, Johanna, The Butcher, Chen, Dehaka, Morales, Lucio, Brightwing, Uther, Thrall, Varian, Kerrigan, Samuro.

Weak Against: Alarak, Anub'arak, Chromie, Garrosh, Genji, Kel'Thuzad, Kael'Thas, Li Ming, Valla, Raynor, Lunara, Gul'dan, Azmodan, Zul'Jin, Nova, Zeratul.

Mind Flay Q Build:

This would be a late game build that would offer tremendous damage at close range, but you would be less effective in the early game.

Void Bolt W Build:

This build offers more immediate damage and enhances his rather poor ranged game. Take this against lots of ranged heroes that typically counter him.

Shiver E Build:

This build is useful if your team lacks wave clear or facing an enemy team that likes to clump together.

Presence Trait Build:

A niche build that works very well against certain heroes and comps.