This deck is built around G'huun the Blood God, specifically we want to draw Malygos and/or Prophet Velen with it so we can setup an OTK with Mind Blast.

Sphere of Sapience is there to ensure we don't draw those two cards before playing Lorekeeper Polkelt.

After obtaining either Malygos or Prophet Velen (or both!) with G'huun the Blood God the combo is pretty easy  to setup.

With Health-cost Malygos:

• Play Malygos for 9 Health (0 mana spent)
• Play Vivid Nightmare on Malygos for up to 3 Mana (3 mana spent)
• Play Gift of Luminance on Malygos for up to 3 Mana (6 mana spent)
• Play Mind Blast for up to 2 Mana dealing 20 Damage to your opponent (8 mana spent)

If you are Shadowreaper Anduin with the hero power discounted by Raza the Chained you can add a shot of Voidform between each step for an extra 2 damage each, adding up to exactly 30 Damage!

With Health-cost Prophet Velen:

• Play Prophet Velen for 7 Health (0 mana spent)
• Play Vivid Nightmare on Velen for up to 3 Mana (3 mana spent)
• Play Gift of Luminance on Velen for up to 3 Mana (6 mana spent)
• Play Mind Blast for up to 2 Mana dealing 40 Damage to your opponent (8 mana spent)

If you are Shadowreaper Anduin with the hero power discounted by Raza the Chained you can add a shot of Voidform between each step for an extra 46 damage total, adding up to 86 Damage! A little bit overkill but I guess it could be relevant against Warrior/Druid.

The dream: Health-cost Prophet Velen AND Malygos:

• Play Malygos for 9 Health (0 mana spent)
• Play Prophet Velen for 7 Health (0 mana spent)
• Play Vivid Nightmare on Velen for up to 3 Mana (3 mana spent)
• Play Gift of Luminance on Velen for up to 3 Mana (6 mana spent)
• Play Mind Blast for up to 2 Mana dealing 80 Damage to your opponent (8 mana spent)

If you are Shadowreaper Anduin with the hero power discounted by Raza the Chained you can add a shot of Voidform between each step for an extra 48 damage total, adding up to 128 Damage! This is the dream with this deck!

This combo is quite late game, so there are some cards to ensure we have something to do before getting there, mainly cheap spell generation to refresh our hero power in the classic Razakus fashion, I also decided to include Yogg-Saron, Master of Fate as a fun card that can also be used as a desperate measure if needed.

Overall I don't think this deck is very competitive, probably needs more card draw/survivabulity, as it stands it's probably too greedy so feel free to experiment and tinker with it.