Vol'Jin by MarioToast

Level 1:

Sight Ward: Replaces Serpent Ward with Sight Ward.
Rain Dance: Quest: Regeneration Globes increase the healing of Rain of Lukou by 25, up to 500.
Reward: After gathering 20 Globes, increase the radius of the rain by 30%.
Rule of Three: Every third Dark Spear will deal 30% increased damage and deal 123.12 (+4% per level) damage in an area.
Gathering Shadows: Quest: Using Small Bad Voodoo to damage enemies with spears in them increase the damage of the surge by 10, up to 200.
Reward: Enemies are also slowed by 25% for 2 seconds when hit by the surge.

Level 4:

Poisoned Spears: Enemies take 11.32 (+4% per level) damage per second as long as they have a spear in them.
Healing Ward: Activate to place a ward on the ground that heals allies in an area for 1.95% of their max Health every second for 10 seconds.
Distant Snake: Increase the cast range of Serpent Ward by 100%.
Muddy Ground: Rain of Lukou turns the ground muddy, slowing enemies by 20%. The mud remains for 1.5 seconds after the rain ends.

Level 7:

Drizzle: When casting Rain of Lukou, a small rain cloud follows Vol'Jin overhead, applying 50% of the effects in a small area around him.

level 10:

Level 13:

Hoodoo Voodoo: Small Bad Voodoo can store 2 charges.

Level 16:

Lightning Cloud: Rain of Lukou fires a lightning bolt at a random enemy Hero in range every 2.75 seconds, dealing 214.21 (+4% per level) damage.

Level 20:

Ssssneak Attack: Hex summons two Serpent Wards to attack the target. Slow increased to 50%, and duration to 2.5 seconds.
Spirits Unleashed: Whenever Vol'Jin uses Small Bad Voodoo, a Spirit is summoned at his side for 10 seconds. The Spirits from Restless Spirits last for 20 seconds.