Mimiron by Nortin

Tier 1
Superheated - Quest: Increase the consecutive hit damage bonus of Flame Vents by .5% each time it damages an enemy hero. up to 10% (for 20% total).
Covering Fire - The VX-001's basic attacks slow targets by 10% for 1 second. More attacks refresh the duration.
Aggravated Assault - Increase the health of Assault Bots by 100%, and they also attack enemies for low damage.
Lock and Load - Increase Mimiron's basic attack speed by 25%. Basic attacks with Titanstrike increase the duration of Mimiron's next vehicle by 1 second, up to 10 seconds.

Tier 2
Repair Mechanisms - Self Repair no longer removes Armor from the Leviathan Mk II. Additionally, it can be used on the secondary ability bar in all other vehicles.
Overclock - Spinning Up also causes other basic abilities to recharge 20% faster. Additionally, it can be used on the secondary ability bar in all other vehicles.
Enhanced Coolant - Flame Suppressant also slows enemies in the target area by 15% for 3 seconds. Additionally, it can be used on the secondary ability bar in all other vehicles.

Tier 3
Minefield - Proximity Mines summons 6 additional mines, but mine damage is reduced by 50%.
Reactive Waves - Increase the area of effect damage of Hand Pulse to 100%.
Energized Plasma - Plasma Ball also increases the movement speed of allies in the target area by 10% for 1 second.
Sniper Rounds - Basic attacks with Titanstrike reveal their target for 3 seconds, and increase the cooldown on Mimiron's basic abilities by 1 second.

Tier 4
Expert Mechanic - Increase the damage of Mimiron's basic vehicles by 20%, and their duration by 5 seconds.
Master Plan - Increase the cooldown of Mimiron's basic abilities to 90 seconds.

Tier 5
Arcane Fire - Flame Vents deals 30% less base damage, but it also reduces the Spell Armor of targets by 10 until its consecutive damage bonus wears off.
Titanstrike Integration - Increase the basic attack range of the VX-001 by 50%.
Orbital Deployment - Assault Bots are now launched at their target location, dealing medium damage where they land.

Tier 6
Reinforced Plating - Increase the maximum health of all vehicles by 20%.
Lock On - If Titanstrike hits the same enemy hero 5 times in a row, they take 30% more damage from Mimiron's next vehicle. Lock On lasts until Mimiron exits a vehicle or activates Lock On on another target.
Jetpack - Adds Jetpack to Mimiron's ability bar.

Tier 7
Big Red Button - Casting Leviathan Mk II spawns a Big Red Button at its location. An allied hero (but not Mimiron) can press the button to give Mimiron 20% increased damage and 10 Armor for 30 seconds. This effect has a 60 second cooldown.
Failsafe Mechanisms - Whenever one of Mimiron's vehicles is destroyed, it deals high damage to all nearby enemies.
Titan's Reach - Upgrade Titanstrike to the bow Titan's Reach. Increases the passive range bonus of Titanstrike to 100% and increases Mimiron's sight range and basic attack damage by 50%.

-Entering a vehicle sets Mimiron's health percentage to 100%. Each vehicle has a different health pool. Exiting the vehicle sets Mimiron's health percentage to what it was before he entered the vehicle.
-Once Mimiron enters a vehicle, he cannot exit it until it is destroyed or the duration runs out.
-Enemies can see Rocket Strike's landing location, so it's easier to dodge.
-Lock and Load can allow V0-7TR-0N to last up to 10 seconds after one of Mimiron's basic abilities comes off cooldown.
-Tier 2 talents cause the affected abilities to appear in the secondary ability bar like an active talent. It applies to all of Mimiron's other vehicles, including V0-7TR-0N.
-Since V0-7TR-0N uses VX-001's basic attack, talents that affect VX-001's basic attack also affect V0-7TR-0N's.
-Expert Mechanic's damage bonuses do not apply to V0-7TR-0N.
-Allied heroes press the Big Red Button by interacting with it, similar to a map objective. Takes .5 seconds to push.

This section contains my explanation and reasoning behind abilities and talents, so if that sounds boring, definitely skip it. I just like writing things maybe a little too much.

Abilities:
Titanstrike (Trait) - Mimiron is intended to be weak outside of his vehicles, but have a lot of range to compensate for being otherwise useless. Also, Titanstrike was a gun created by Mimiron for another titan watcher, so it kind of matches lore wise.

Leviathan Mk II (Q) - Mimiron's tank mode, both mechanically and visually. The basic attack is intended to allude to the original Flame Leviathan, who knocked enemies back with a battering ram.
Flame Vents (Q - Q) - Main damage ability for Leviathan Mk II. Good since it wants to be in the middle of things, and punishes enemies for staying too long.
Proximity Mines (Q - W) - Area control that punishes enemies with damage. Not too much to say.
Self Repair (Q - E) - Makes the Leviathan Mk II able to stay in battle longer.

VX-001 (W) - Mimiron's main damage form. Deals large damage, but can be punished by either avoiding it, since it can't chase, or attacking it, since it can't escape.
Hand Pulse (W - Q) - One of the VX-001's abilities in the raid. Adds some area of effect damage.
Spinning Up (W - W) - Another one of VX-001's abilities in the raid. Essentially forces opponents to flee or take massive damage.
Rocket Strike (W - E) - A particularly intimidating ability from the Mimiron fight in World of Warcraft, which dealt so much damage it was expressed in scientific notation. Definitely had to tone that down, but has a similar high damage but easy to dodge mechanic.

Aerial Command Unit (E) - Intended to be hard to catch and apply lots of area of effect buffs and debuffs. Also, it's both entertaining and disturbing, as it is a flying replica of Mimiron's head.
Plasma Ball (E - Q - Low cooldown control ability, to make up for the fact that the Aerial Command Unit has no basic attack.
Assault Bot (E - W) - More control that annoys enemies. Should be a main priority for enemies to deal with.
Flame Suppressant (E - E) - Provides the area of effect buff in the Aerial Command Unit's default kit. Also an interesting counter to damage over time, since few exist.

V0-7TR-0N (R) - The ultimate form, combining the strengths of all other vehicles. Intended to be used rarely and to great effect, since juggling all vehicles on cooldown may be difficult.

Talents:

Tier 1
Superheated - I wanted a talent for each form that is also used in V0-7TR-0N, so this is the first one. Quest talents are good, and more damage is good.
Covering Fire - Slightly improved basic attacks, not much to say.
Aggravated Assault - Makes Assault Bots much more versatile and more threatening.
Lock and Load - If Mimiron wants more value out of a certain vehicle, this ability provides it. And attack speed is nice.

Tier 2
Repair Mechanisms - I wanted Tier 2 talents to extend abilities to other forms, so this is that. Makes Repair Mechanisms better and available to other forms. May be too strong, but the long cooldown should balance it.
Overclock - Attack speed on the Leviathan Mk II is questionable, but cooldown reduction for all forms and the attack speed for V0-7TR-0N are all good.
Enhanced Coolant - Not much to say. Adds slow. All vehicles have support capability.

Tier 3
Minefield - Provides potentially more damage and zoning from Proximity Mines.
Reactive Waves - More area of effect for the VX-001. That's it.
Energized Plasma - Adds more support to the Aerial Command Unit.
Sniper Rounds - Revealing enemies is good, and since Mimiron won't be outside of a vehicle too often it should be balanced. Also, the cooldown increase can give Mimiron a bigger window between vehicles while still getting a good V0-7TR-0N.

Tier 4
Expert Mechanic - Since Mimiron has his heroic at level 1, I went for a Tracer-type Tier 4, where you get passives that augment different playstyles. This one is for preferring individual vehicles over V0-7TR-0N. Each vehicle is better, but it's harder to get a good duration for V0-7TR-0N.
Master Plan - For V0-7TR-0N based builds. Increasing basic ability cooldowns directly increases the duration of V0-7TR-0N, so this gives more time in that form.

Tier 5
Arcane Fire - Allows Mimiron to trade direct damage for utility for his team.
Titanstrike Integration - More range makes VX-001 better at zoning, and V0-7TR-0N more dangerous in general.
Orbital Deployment - Gives the Aerial Command Unit more damage potential.

Tier 6
Reinforced Plating - More general durability for all of Mimiron's vehicles.
Lock On - This talent is intended to reward Mimiron for preparing for a fight with his normal basic attack before activating his vehicles. 30% may be too strong, so that might change.
Jetpack - Gives Mimiron an escape for when his vehicles don't work out. Good for situations where escaping is better than feeding more kills to your opponents through vehicles.

Tier 7
Big Red Button - A reference to heroic mode in the original Mimiron raid fight, where players could press a big red button, and Mimiron would scold them for doing so. Adds more team play to Mimiron's kit, and can be a good boost for fights.
Failsafe Mechanisms - For when Mimiron's vehicles are destroyed often.
Titan's Reach - Based on the hidden appearance for the artifact weapon Titanstrike in World of Warcraft. Allows Mimiron to make better use of his basic attack and corresponding talents.