The Overmind by Fillipk

Level 1

Speedlings: Zerglings have 33% increased movement speed

Banelings: Zerglings can now morph into banelings which have 115 (+4% per level) health and explode for 50 (+4% per level) damage in an area, they deal double damage to minions and monsters. Banelings take 8 seconds to morph in and can be killed while morphing in.

A tougher Body: The Overmind has 50% more health (does not work on Towers of Doom that would be OP)

Psionic Shields: Cerbrates have one charge of 50% spellblock every 6 seconds

Level 4

Ravagers: Roaches can be morphed into Ravagers which have 625 (+4% per level) health and deal 38 (+4% per level) damage with a range of 4. Ravagers have the ability to launch corrosive bile at a point, this point is telegraphed on the map and after 1.5 seconds lands and deals 225 (+4% per level) damage. Morphing a ravager takes 12 seconds, 4 supply, and ravagers can be killed while morphing.

Armored Plating: Roaches take half damage from minions and mercenaries and any mercenaries within a cerebrate's influence can be controlled

A Stronger Body: Increase the Overmind's damage by 50%

Psionic strength: Increase the influence zones of Cerebrates by 33%

Burrow: Allows Zerg units to burrow, stealthing them but not making them immune to damage, Flying units cannot be burrowed and Roaches and infestors can move while burrowed

Level 7

Lurkers: Allows hydralisks to morph into Lurkers which have 375 (+4% per level) health and deal 80 (+4% per level) damage in a line with a range of 5. Lurkers have the ability to burrow which stealths them and they can only attack while burrowed. Morphing in a Lurker takes 15 seconds and 4 supply

Muscular Augments: Increase the hydralisk's range by 1 and their movespeed by 15%

Assimilate Mutalisks: The Overmind gains the ability to produce Mutalisks. Mutalisks have 380 (+4% per level) health and do 30 (+4% per level) damage at a range of 5.5. Mutalisks can fly over terrain and their attacks bounce to 2 additional targets dealing half damage on the first bounce and quarter damage on the third bounce. The Overmind can build 2 Mutalisks every 10 seconds and Mutalisks take up 5 supply each.

Mental Capacity: Increase the supply of the Overmind by 10 and the supply each Cerebrates by 5

Level 10

Assimilate Broodlord

Assimilate Brutalisk

Level 13

Assimilate Queen: The Overmind gains the ability to produce Queens. Queens have 625 (+4% per level) health and do 48 (+4% per level) damage with a range of 5.5. The Overmind can produce 1 Queen every 10 seconds, Queens take up 6 supply.

Queens have the ability to cast transfuse on a friendly building or ally. Transfuse heals the target for 325 (+4% per level) health and has a 15 second cooldown. the Heal is three times as effective if used on a building or the Overmind.

Assimilate Viper: The Overmind gains the ability to spawn Vipers. Vipers have 625 (+4% per level) health and no auto attack and can fly over terrain. The Overmind can produce one viper every 15 seconds, Vipers take up 12 supply.

Vipers have the ability to cast grab. This launches a tongue that pulls the first enemy hit to the viper at about half the range of a stitches hook. This ability is on a 20 second cooldown.

Assimilate Infestor: The Overmind gains the ability to produce Infestors. Infestors have 625 (+4% per level health and no Auto attack. The Overmind can produce one Infestor every 18 seconds , Infestors take up 14 supply.

Infestors have the ability to cast Fungal Growth while not burrowed. fungal growth roots all enemies in an area (size of T***'s psionic storm) for 1 second, this ability is on a 20 second cooldown.

Infest Structure: The Overmind Infests a structure fully restoring it's ammo and increasing its attack speed by 100% for 5 seconds. 60 second cooldown.

Level 16

Reactors?: The Overmind can produce two units at once

Hasty Eggs: Units produce 60% faster

Past Techniques: The Overmind can select any two talents from from previous non-ult tiers

True Power: The Overmind can attack two targets

Level 20

The Brood: Brood Lords cost 12 supply and are produced 10 seconds faster

Assimilate Defiler: The Overmind Gains the ability to produce Defilers. Defilers have 2,100 (+4% per level) health and no auto attack. The Overmind can produce one Defiler every 45 seconds and they cost 25 supply

Defilers have the ability to use Dark Swarm which protects all units within if from range Auto Attacks and provides allies within the cloud 50% spell resistance. the Cloud lasts 4 seconds and is on a 12 second cooldown.

Defilers also have the ability to use plague which deals 200 (+4% per level) damage per second to enemies within the plagued area. The plague lasts for 8 seconds and is on a 10 second cooldown

Warp Factor 9: Warp Rifts last 10 seconds and the cooldown is reduced by 30 seconds:

Call of the Zerg: Instantly spawn 30 supply worth of random unlocked Zerg at the Overmind 90 second cooldown